diff --git a/chrome/content/zotero/xpcom/collectionTreeView.js b/chrome/content/zotero/xpcom/collectionTreeView.js
index 6e8c1428b..3c46c7ccf 100644
--- a/chrome/content/zotero/xpcom/collectionTreeView.js
+++ b/chrome/content/zotero/xpcom/collectionTreeView.js
@@ -235,24 +235,8 @@ Zotero.CollectionTreeView.prototype.refresh = function()
  */
 Zotero.CollectionTreeView.prototype.reload = function()
 {
-	var openCollections = [];
-	
-	for (var i=0; i<this.rowCount; i++) {
-		if (this.isContainer(i) && this.isContainerOpen(i)) {
-			openCollections.push(this._getItemAtRow(i).ref.id);
-		}
-	}
-	
 	this._treebox.beginUpdateBatch();
 	this.refresh();
-	
-	for(var i = 0; i < openCollections.length; i++)
-	{
-		var row = this._collectionRowMap[openCollections[i]];
-		if (typeof row != 'undefined') {
-			this.toggleOpenState(row);
-		}
-	}
 	this._treebox.invalidate();
 	this._treebox.endUpdateBatch();
 }
@@ -360,9 +344,9 @@ Zotero.CollectionTreeView.prototype.notify = function(action, type, ids)
 		{
 			case 'collection':
 				var collection = Zotero.Collections.get(ids);
-				var collectionID = collection.id;
+				
 				// Open container if creating subcollection
-				var parentID = collection.getParent();
+				var parentID = collection.parent;
 				if (parentID) {
 					if (!this.isContainerOpen(this._collectionRowMap[parentID])){
 						this.toggleOpenState(this._collectionRowMap[parentID]);
@@ -374,7 +358,7 @@ Zotero.CollectionTreeView.prototype.notify = function(action, type, ids)
 					this.rememberSelection(savedSelection);
 					break;
 				}
-				this.selection.select(this._collectionRowMap[collectionID]);
+				this.selection.select(this._collectionRowMap[collection.id]);
 				break;
 				
 			case 'search':
@@ -1259,27 +1243,42 @@ Zotero.CollectionTreeView.prototype.canDrop = function(row, orient, dragData)
 			return true;
 		}
 		else if (dataType == 'zotero/collection') {
-			// Collections cannot be dropped on themselves
-			if (data[0] == itemGroup.ref.id) {
-				return false;
-			}
-			
-			// Nor in their children
-			if (Zotero.Collections.get(data[0]).hasDescendent('collection', itemGroup.ref.id)) {
-				return false;
-			}
-			
 			var col = Zotero.Collections.get(data[0]);
 			
-			// Nor, at least for now, on another group
-			if (itemGroup.isWithinGroup()) {
-				if (itemGroup.ref.libraryID != col.libraryID) {
+			if (itemGroup.ref.libraryID == col.libraryID) {
+				// Collections cannot be dropped on themselves
+				if (data[0] == itemGroup.ref.id) {
+					return false;
+				}
+				
+				// Nor in their children
+				if (Zotero.Collections.get(data[0]).hasDescendent('collection', itemGroup.ref.id)) {
 					return false;
 				}
 			}
-			// Nor from a group library to the local library
-			else if (col.libraryID) {
-				return false;
+			// Dragging a collection to a different library
+			else {
+				// Allow cross-library drag only to root library and collections
+				if (!itemGroup.isLibrary(true) && !itemGroup.isCollection()) {
+					return false;
+				}
+				
+				// Disallow if linked collection already exists
+				if (col.getLinkedCollection(itemGroup.ref.libraryID)) {
+					return false;
+				}
+				
+				var descendents = col.getDescendents(false, 'collection');
+				for each(var descendent in descendents) {
+					descendent = Zotero.Collections.get(descendent.id);
+					// Disallow if linked collection already exists for any subcollections
+					//
+					// If this is allowed in the future for the root collection,
+					// need to allow drag only to root
+					if (descendent.getLinkedCollection(itemGroup.ref.libraryID)) {
+						return false;
+					}
+				}
 			}
 			
 			return true;
@@ -1303,15 +1302,202 @@ Zotero.CollectionTreeView.prototype.drop = function(row, orient)
 	var data = dragData.data;
 	var itemGroup = this._getItemAtRow(row);
 	
-	if(dataType == 'zotero/collection')
-	{
-		var targetCollectionID;
-		if (itemGroup.isCollection()) {
-			targetCollectionID = itemGroup.ref.id;
+	function copyItem (item, targetLibraryID) {
+		// Check if there's already a copy of this item in the library
+		var linkedItem = item.getLinkedItem(targetLibraryID);
+		if (linkedItem) {
+			return linkedItem.id;
+			
+			/*
+			// TODO: support tags, related, attachments, etc.
+			
+			// Overlay source item fields on unsaved clone of linked item
+			var newItem = item.clone(false, linkedItem.clone(true));
+			newItem.setField('dateAdded', item.dateAdded);
+			newItem.setField('dateModified', item.dateModified);
+			
+			var diff = newItem.diff(linkedItem, false, ["dateAdded", "dateModified"]);
+			if (!diff) {
+				// Check if creators changed
+				var creatorsChanged = false;
+				
+				var creators = item.getCreators();
+				var linkedCreators = linkedItem.getCreators();
+				if (creators.length != linkedCreators.length) {
+					Zotero.debug('Creators have changed');
+					creatorsChanged = true;
+				}
+				else {
+					for (var i=0; i<creators.length; i++) {
+						if (!creators[i].ref.equals(linkedCreators[i].ref)) {
+							Zotero.debug('changed');
+							creatorsChanged = true;
+							break;
+						}
+					}
+				}
+				if (!creatorsChanged) {
+					Zotero.debug("Linked item hasn't changed -- skipping conflict resolution");
+					continue;
+				}
+			}
+			toReconcile.push([newItem, linkedItem]);
+			continue;
+			*/
 		}
+		
+		// Standalone attachment
+		if (item.isAttachment()) {
+			return Zotero.Attachments.copyAttachmentToLibrary(item, targetLibraryID);
+		}
+		
+		// Create new unsaved clone item in target library
+		var newItem = new Zotero.Item(item.itemTypeID);
+		newItem.libraryID = targetLibraryID;
+		// DEBUG: save here because clone() doesn't currently work on unsaved tagged items
+		var id = newItem.save();
+		newItem = Zotero.Items.get(id);
+		item.clone(false, newItem);
+		newItem.save();
+		//var id = newItem.save();
+		//var newItem = Zotero.Items.get(id);
+		
+		// Record link
+		item.addLinkedItem(newItem);
+		var newID = id;
+		
+		if (item.isNote()) {
+			return newID;
+		}
+		
+		// For regular items, add child items if prefs and permissions allow
+		
+		// Child notes
+		if (Zotero.Prefs.get('groups.copyChildNotes')) {
+			var noteIDs = item.getNotes();
+			var notes = Zotero.Items.get(noteIDs);
+			for each(var note in notes) {
+				var newNote = new Zotero.Item('note');
+				newNote.libraryID = targetLibraryID;
+				// DEBUG: save here because clone() doesn't currently work on unsaved tagged items
+				var id = newNote.save();
+				newNote = Zotero.Items.get(id);
+				note.clone(false, newNote);
+				newNote.setSource(newItem.id);
+				newNote.save();
+				
+				note.addLinkedItem(newNote);
+			}
+		}
+		
+		// Child attachments
+		var copyChildLinks = Zotero.Prefs.get('groups.copyChildLinks');
+		var copyChildFileAttachments = Zotero.Prefs.get('groups.copyChildFileAttachments');
+		if (copyChildLinks || copyChildFileAttachments) {
+			var attachmentIDs = item.getAttachments();
+			var attachments = Zotero.Items.get(attachmentIDs);
+			for each(var attachment in attachments) {
+				var linkMode = attachment.attachmentLinkMode;
+				
+				// Skip linked files
+				if (linkMode == Zotero.Attachments.LINK_MODE_LINKED_FILE) {
+					continue;
+				}
+				
+				// Skip imported files if we don't have pref and permissions
+				if (linkMode == Zotero.Attachments.LINK_MODE_LINKED_URL) {
+					if (!copyChildLinks) {
+						Zotero.debug("Skipping child link attachment on drag");
+						continue;
+					}
+				}
+				else {
+					if (!copyChildFileAttachments || !itemGroup.filesEditable) {
+						Zotero.debug("Skipping child file attachment on drag");
+						continue;
+					}
+				}
+				
+				Zotero.Attachments.copyAttachmentToLibrary(attachment, targetLibraryID, newItem.id);
+			}
+		}
+		
+		return newID;
+	}
+	
+	
+	var targetLibraryID = itemGroup.isWithinGroup() ? itemGroup.ref.libraryID : null;
+	var targetCollectionID = itemGroup.isCollection() ? itemGroup.ref.id : false;
+	
+	if (dataType == 'zotero/collection') {
 		var droppedCollection = Zotero.Collections.get(data[0]);
-		droppedCollection.parent = targetCollectionID;
-		droppedCollection.save();
+		
+		// Collection drag between libraries
+		if (targetLibraryID != droppedCollection.libraryID) {
+			Zotero.DB.beginTransaction();
+			
+			function copyCollections(descendents, parent, addItems) {
+				for each(var desc in descendents) {
+					// Collections
+					if (desc.type == 'collection') {
+						var c = Zotero.Collections.get(desc.id);
+						
+						var newCollection = new Zotero.Collection;
+						newCollection.libraryID = targetLibraryID;
+						c.clone(false, newCollection);
+						if (parent) {
+							newCollection.parent = parent;
+						}
+						var collectionID = newCollection.save();
+						
+						// Record link
+						c.addLinkedCollection(newCollection);
+						
+						// Recursively copy subcollections
+						if (desc.children.length) {
+							copyCollections(desc.children, collectionID, addItems);
+						}
+					}
+					// Items
+					else {
+						var item = Zotero.Items.get(desc.id);
+						var id = copyItem(item, targetLibraryID);
+						// Mark copied item for adding to collection
+						if (parent) {
+							if (!addItems[parent]) {
+								addItems[parent] = [];
+							}
+							addItems[parent].push(id);
+						}
+					}
+				}
+				
+				return collectionID;
+			}
+			
+			var collections = [{
+				id: droppedCollection.id,
+				children: droppedCollection.getDescendents(true),
+				type: 'collection'
+			}];
+			
+			var addItems = {};
+			copyCollections(collections, targetCollectionID, addItems);
+			for (var collectionID in addItems) {
+				var collection = Zotero.Collections.get(collectionID);
+				collection.addItems(addItems[collectionID]);
+			}
+			
+			// TODO: add subcollections and subitems, if they don't already exist,
+			// and display a warning if any of the subcollections already exist
+			
+			Zotero.DB.commitTransaction();
+		}
+		// Collection drag within a library
+		else {
+			droppedCollection.parent = targetCollectionID;
+			droppedCollection.save();
+		}
 	}
 	else if (dataType == 'zotero/item') {
 		var ids = data;
@@ -1319,13 +1505,6 @@ Zotero.CollectionTreeView.prototype.drop = function(row, orient)
 			return;
 		}
 		
-		if (itemGroup.isWithinGroup()) {
-			var targetLibraryID = itemGroup.ref.libraryID;
-		}
-		else {
-			var targetLibraryID = null;
-		}
-		
 		if(itemGroup.isBucket()) {
 			itemGroup.ref.uploadItems(ids);
 			return;
@@ -1335,6 +1514,7 @@ Zotero.CollectionTreeView.prototype.drop = function(row, orient)
 		
 		var items = Zotero.Items.get(ids);
 		if (!items) {
+			Zotero.DB.commitTransaction();
 			return;
 		}
 		
@@ -1364,131 +1544,9 @@ Zotero.CollectionTreeView.prototype.drop = function(row, orient)
 		if (!sameLibrary) {
 			var toReconcile = [];
 			
+			var newIDs = [];
 			for each(var item in newItems) {
-				// Check if there's already a copy of this item in the library
-				var linkedItem = item.getLinkedItem(targetLibraryID);
-				if (linkedItem) {
-					// Add linked item to target collection rather than copying
-					if (itemGroup.isCollection()) {
-						itemGroup.ref.addItem(linkedItem.id);
-						continue;
-					}
-					
-					/*
-					// TODO: support tags, related, attachments, etc.
-					
-					// Overlay source item fields on unsaved clone of linked item
-					var newItem = item.clone(false, linkedItem.clone(true));
-					newItem.setField('dateAdded', item.dateAdded);
-					newItem.setField('dateModified', item.dateModified);
-					
-					var diff = newItem.diff(linkedItem, false, ["dateAdded", "dateModified"]);
-					if (!diff) {
-						// Check if creators changed
-						var creatorsChanged = false;
-						
-						var creators = item.getCreators();
-						var linkedCreators = linkedItem.getCreators();
-						if (creators.length != linkedCreators.length) {
-							Zotero.debug('Creators have changed');
-							creatorsChanged = true;
-						}
-						else {
-							for (var i=0; i<creators.length; i++) {
-								if (!creators[i].ref.equals(linkedCreators[i].ref)) {
-									Zotero.debug('changed');
-									creatorsChanged = true;
-									break;
-								}
-							}
-						}
-						if (!creatorsChanged) {
-							Zotero.debug("Linked item hasn't changed -- skipping conflict resolution");
-							continue;
-						}
-					}
-					toReconcile.push([newItem, linkedItem]);
-					continue;
-					*/
-				}
-				
-				// Standalone attachment
-				if (item.isAttachment()) {
-					var id = Zotero.Attachments.copyAttachmentToLibrary(item, targetLibraryID);
-					newIDs.push(id);
-					continue;
-				}
-				
-				// Create new unsaved clone item in target library
-				var newItem = new Zotero.Item(item.itemTypeID);
-				newItem.libraryID = targetLibraryID;
-				// DEBUG: save here because clone() doesn't currently work on unsaved tagged items
-				var id = newItem.save();
-				newItem = Zotero.Items.get(id);
-				item.clone(false, newItem);
-				newItem.save();
-				//var id = newItem.save();
-				//var newItem = Zotero.Items.get(id);
-				
-				// Record link
-				item.addLinkedItem(newItem);
-				newIDs.push(id);
-				
-				if (item.isNote()) {
-					continue;
-				}
-				
-				// For regular items, add child items if prefs and permissions allow
-				
-				// Child notes
-				if (Zotero.Prefs.get('groups.copyChildNotes')) {
-					var noteIDs = item.getNotes();
-					var notes = Zotero.Items.get(noteIDs);
-					for each(var note in notes) {
-						var newNote = new Zotero.Item('note');
-						newNote.libraryID = targetLibraryID;
-						// DEBUG: save here because clone() doesn't currently work on unsaved tagged items
-						var id = newNote.save();
-						newNote = Zotero.Items.get(id);
-						note.clone(false, newNote);
-						newNote.setSource(newItem.id);
-						newNote.save();
-						
-						note.addLinkedItem(newNote);
-					}
-				}
-				
-				// Child attachments
-				var copyChildLinks = Zotero.Prefs.get('groups.copyChildLinks');
-				var copyChildFileAttachments = Zotero.Prefs.get('groups.copyChildFileAttachments');
-				if (copyChildLinks || copyChildFileAttachments) {
-					var attachmentIDs = item.getAttachments();
-					var attachments = Zotero.Items.get(attachmentIDs);
-					for each(var attachment in attachments) {
-						var linkMode = attachment.attachmentLinkMode;
-						
-						// Skip linked files
-						if (linkMode == Zotero.Attachments.LINK_MODE_LINKED_FILE) {
-							continue;
-						}
-						
-						// Skip imported files if we don't have pref and permissions
-						if (linkMode == Zotero.Attachments.LINK_MODE_LINKED_URL) {
-							if (!copyChildLinks) {
-								Zotero.debug("Skipping child link attachment on drag");
-								continue;
-							}
-						}
-						else {
-							if (!copyChildFileAttachments || !itemGroup.filesEditable) {
-								Zotero.debug("Skipping child file attachment on drag");
-								continue;
-							}
-						}
-						
-						var id = Zotero.Attachments.copyAttachmentToLibrary(attachment, targetLibraryID, newItem.id);
-					}
-				}
+				newIDs.push(copyItem(item, libraryID));
 			}
 			
 			if (toReconcile.length) {
@@ -1529,8 +1587,10 @@ Zotero.CollectionTreeView.prototype.drop = function(row, orient)
 			}
 		}
 		
-		if (newIDs.length && itemGroup.isCollection()) {
-			itemGroup.ref.addItems(newIDs);
+		// Add items to target collection
+		if (targetCollectionID) {
+			var collection = Zotero.Collections.get(targetCollectionID);
+			collection.addItems(newIDs);
 		}
 		
 		Zotero.DB.commitTransaction();
diff --git a/chrome/content/zotero/xpcom/data/collection.js b/chrome/content/zotero/xpcom/data/collection.js
index 6b749bfea..0e2a90c1f 100644
--- a/chrome/content/zotero/xpcom/data/collection.js
+++ b/chrome/content/zotero/xpcom/data/collection.js
@@ -896,6 +896,40 @@ Zotero.Collection.prototype.diff = function (collection, includeMatches, ignoreO
 }
 
 
+/**
+ * Returns an unsaved copy of the collection
+ *
+ * Does not copy parent collection or child items
+ *
+ * @param	{Boolean}		[includePrimary=false]
+ * @param	{Zotero.Collection} [newCollection=null]
+ */
+Zotero.Collection.prototype.clone = function (includePrimary, newCollection) {
+	Zotero.debug('Cloning collection ' + this.id);
+	
+	if (newCollection) {
+		var sameLibrary = newCollection.libraryID == this.libraryID;
+	}
+	else {
+		var newCollection = new Zotero.Collection;
+		var sameLibrary = true;
+		
+		if (includePrimary) {
+			newCollection.id = this.id;
+			newCollection.libraryID = this.libraryID;
+			newCollection.key = this.key;
+			
+			// TODO: This isn't used, but if it were, it should probably include
+			// parent collection and child items
+		}
+	}
+	
+	newCollection.name = this.name;
+	
+	return newCollection;
+}
+
+
 /**
 * Deletes collection and all descendent collections (and optionally items)
 **/
@@ -930,6 +964,10 @@ Zotero.Collection.prototype.erase = function(deleteItems) {
 		Zotero.Items.erase(del);
 	}
 	
+	// Remove relations
+	var uri = Zotero.URI.getCollectionURI(this);
+	Zotero.Relations.eraseByURIPrefix(uri);
+	
 	var placeholders = collections.map(function () '?').join();
 	
 	// Remove item associations for all descendent collections
@@ -1095,6 +1133,60 @@ Zotero.Collection.prototype.getDescendents = function(nested, type, includeDelet
 }
 
 
+/**
+ * Return a collection in the specified library equivalent to this collection
+ */
+Zotero.Collection.prototype.getLinkedCollection = function (libraryID) {
+	if (libraryID == this.libraryID) {
+		throw ("Collection is already in library " + libraryID + " in Zotero.Collection.getLinkedCollection()");
+	}
+	
+	var predicate = Zotero.Relations.linkedObjectPredicate;
+	var collectionURI = Zotero.URI.getCollectionURI(this);
+	var links = Zotero.Relations.getObject(collectionURI, predicate, false).concat(
+		Zotero.Relations.getSubject(false, predicate, collectionURI)
+	);
+	
+	if (!links.length) {
+		return false;
+	}
+	
+	if (libraryID) {
+		var libraryCollectionPrefix = Zotero.URI.getLibraryURI(libraryID) + "/collections/";
+	}
+	else {
+		var libraryCollectionPrefix = Zotero.URI.getCurrentUserURI() + "/collections/";
+	}
+	for each(var link in links) {
+		if (link.indexOf(libraryCollectionPrefix) == 0) {
+			var collection = Zotero.URI.getURICollection(link);
+			if (!collection) {
+				Zotero.debug("Referenced linked collection '" + link + "' not found in Zotero.Collection.getLinkedCollection()", 2);
+				continue;
+			}
+			return collection;
+		}
+	}
+	return false;
+}
+
+
+Zotero.Collection.prototype.addLinkedCollection = function (collection) {
+	var url1 = Zotero.URI.getCollectionURI(this);
+	var url2 = Zotero.URI.getCollectionURI(collection);
+	var predicate = Zotero.Relations.linkedObjectPredicate;
+	if (Zotero.Relations.getByURIs(url1, predicate, url2).length
+			|| Zotero.Relations.getByURIs(url2, predicate, url1).length) {
+		Zotero.debug("Collections " + this.key + " and " + collection.key + " are already linked");
+		return false;
+	}
+	Zotero.Relations.add(null, url1, predicate, url2);
+}
+
+//
+// Private methods
+//
+
 Zotero.Collection.prototype._prepFieldChange = function (field) {
 	if (!this._changed) {
 		this._changed = {};
diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index d16ee2320..c0ce933ab 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -3548,12 +3548,12 @@ Zotero.Item.prototype.getLinkedItem = function (libraryID) {
 		throw ("Item is already in library " + libraryID + " in Zotero.Item.getLinkedItem()");
 	}
 	
-	var predicate = Zotero.Items.linkedItemPredicate;
+	var predicate = Zotero.Relations.linkedObjectPredicate;
 	var itemURI = Zotero.URI.getItemURI(this);
 	var links = Zotero.Relations.getObject(itemURI, predicate, false).concat(
 		Zotero.Relations.getSubject(false, predicate, itemURI)
 	);
-	Zotero.debug(links);
+	
 	if (!links.length) {
 		return false;
 	}
@@ -3581,7 +3581,7 @@ Zotero.Item.prototype.getLinkedItem = function (libraryID) {
 Zotero.Item.prototype.addLinkedItem = function (item) {
 	var url1 = Zotero.URI.getItemURI(this);
 	var url2 = Zotero.URI.getItemURI(item);
-	var predicate = Zotero.Items.linkedItemPredicate;
+	var predicate = Zotero.Relations.linkedObjectPredicate;
 	if (Zotero.Relations.getByURIs(url1, predicate, url2).length
 			|| Zotero.Relations.getByURIs(url2, predicate, url1).length) {
 		Zotero.debug("Items " + this.key + " and " + item.key + " are already linked");
diff --git a/chrome/content/zotero/xpcom/data/items.js b/chrome/content/zotero/xpcom/data/items.js
index 241dc4f95..a26f814b6 100644
--- a/chrome/content/zotero/xpcom/data/items.js
+++ b/chrome/content/zotero/xpcom/data/items.js
@@ -52,7 +52,6 @@ Zotero.Items = new function() {
 		return _primaryFields;
 	});
 	
-	this.__defineGetter__('linkedItemPredicate', function () "owl:sameAs");
 	
 	// Private members
 	var _cachedFields = [];
diff --git a/chrome/content/zotero/xpcom/data/relations.js b/chrome/content/zotero/xpcom/data/relations.js
index 3254cbfab..70f0ab431 100644
--- a/chrome/content/zotero/xpcom/data/relations.js
+++ b/chrome/content/zotero/xpcom/data/relations.js
@@ -27,6 +27,7 @@ Zotero.Relations = new function () {
 	Zotero.DataObjects.apply(this, ['relation']);
 	this.constructor.prototype = new Zotero.DataObjects();
 	
+	this.__defineGetter__('linkedObjectPredicate', function () "owl:sameAs");
 	this.__defineGetter__('deletedItemPredicate', function () 'dc:isReplacedBy');
 	
 	var _namespaces = {
@@ -226,7 +227,10 @@ Zotero.Relations = new function () {
 				if (uri.indexOf(prefix) == -1) {
 					continue;
 				}
-				if (!Zotero.URI.getURIItem(uri)) {
+				if (uri.indexOf(/\/items\//) != -1 && !Zotero.URI.getURIItem(uri)) {
+					this.eraseByURI(uri);
+				}
+				if (uri.indexOf(/\/collections\//) != -1 && !Zotero.URI.getURICollection(uri)) {
 					this.eraseByURI(uri);
 				}
 			}
diff --git a/chrome/content/zotero/xpcom/uri.js b/chrome/content/zotero/xpcom/uri.js
index ede06f4e5..8f65a5462 100644
--- a/chrome/content/zotero/xpcom/uri.js
+++ b/chrome/content/zotero/xpcom/uri.js
@@ -131,6 +131,28 @@ Zotero.URI = new function () {
 	}
 	
 	
+	/**
+	 * Return URI of collection, which might be a local URI if user hasn't synced
+	 */
+	this.getCollectionURI = function (collection) {
+		if (collection.libraryID) {
+			var baseURI = this.getLibraryURI(collection.libraryID);
+		}
+		else {
+			var baseURI =  this.getCurrentUserURI();
+		}
+		return baseURI + "/collections/" + collection.key;
+	}
+	
+	
+	/**
+	 * Get path portion of collection URI (e.g., users/6/collections/ABCD1234 or groups/1/collections/ABCD1234)
+	 */
+	this.getCollectionPath = function (collection) {
+		return this.getLibraryPath(collection.libraryID) + "/collections/" + collection.key;
+	}
+	
+	
 	this.getGroupsURL = function () {
 		return ZOTERO_CONFIG.WWW_BASE_URL + "groups";
 	}
@@ -156,17 +178,42 @@ Zotero.URI = new function () {
 	 * @param	{Zotero.Item|FALSE}
 	 */
 	this.getURIItem = function (itemURI) {
+		return this._getURIObject(itemURI, 'item');
+	}
+	
+	
+	/**
+	 * Convert a collection URI into a collection
+	 *
+	 * @param	{String}				collectionURI
+	 * @param	{Zotero.Collection|FALSE}
+	 */
+	this.getURICollection = function (collectionURI) {
+		return this._getURIObject(collectionURI, 'collection');
+	}
+	
+	
+	/**
+	 * Convert an object URI into an object (item, collection, etc.)
+	 *
+	 * @param	{String}				objectURI
+	 * @param	{Zotero.Item|Zotero.Collection|FALSE}
+	 */
+	this._getURIObject = function (objectURI, type) {
+		var Types = type[0].toUpperCase() + type.substr(1) + 's';
+		var types = Types.toLowerCase();
+		
 		var libraryType = null;
 		
 		// If this is a local URI, compare to the local user key
-		if (itemURI.match(/\/users\/local\//)) {
+		if (objectURI.match(/\/users\/local\//)) {
 			// For now, at least, don't check local id
 			/*
 			var localUserURI = this.getLocalUserURI();
 			if (localUserURI) {
 				localUserURI += "/";
-				if (itemURI.indexOf(localUserURI) == 0) {
-					itemURI = itemURI.substr(localUserURI.length);
+				if (objectURI.indexOf(localUserURI) == 0) {
+					objectURI = objectURI.substr(localUserURI.length);
 					var libraryType = 'user';
 					var id = null;
 				}
@@ -178,29 +225,30 @@ Zotero.URI = new function () {
 		
 		// If not found, try global URI
 		if (!libraryType) {
-			if (itemURI.indexOf(_baseURI) != 0) {
-				throw ("Invalid base URI '" + itemURI + "' in Zotero.URI.getURIItem()");
+			if (objectURI.indexOf(_baseURI) != 0) {
+				throw ("Invalid base URI '" + objectURI + "' in Zotero.URI._getURIObject()");
 			}
-			itemURI = itemURI.substr(_baseURI.length);
+			objectURI = objectURI.substr(_baseURI.length);
 			var typeRE = /^(users|groups)\/([0-9]+)\//;
-			var matches = itemURI.match(typeRE);
+			var matches = objectURI.match(typeRE);
 			if (!matches) {
-				throw ("Invalid library URI '" + itemURI + "' in Zotero.URI.getURIItem()");
+				throw ("Invalid library URI '" + objectURI + "' in Zotero.URI._getURIObject()");
 			}
 			var libraryType = matches[1].substr(0, matches[1].length-1);
 			var id = matches[2];
-			itemURI = itemURI.replace(typeRE, '');
+			objectURI = objectURI.replace(typeRE, '');
 		}
 		
-		// TODO: itemID-based URI?
-		var matches = itemURI.match(/items\/([A-Z0-9]{8})/);
+		// TODO: objectID-based URI?
+		var re = new RegExp(types + "\/([A-Z0-9]{8})");
+		var matches = objectURI.match(re);
 		if (!matches) {
-			throw ("Invalid item URI '" + itemURI + "' in Zotero.URI.getURIItem()");
+			throw ("Invalid object URI '" + objectURI + "' in Zotero.URI._getURIObject()");
 		}
-		var itemKey = matches[1];
+		var objectKey = matches[1];
 		
 		if (libraryType == 'user') {
-			return Zotero.Items.getByLibraryAndKey(null, itemKey);
+			return Zotero[Types].getByLibraryAndKey(null, objectKey);
 		}
 		
 		if (libraryType == 'group') {
@@ -208,7 +256,7 @@ Zotero.URI = new function () {
 				return false;
 			}
 			var libraryID = Zotero.Groups.getLibraryIDFromGroupID(id);
-			return Zotero.Items.getByLibraryAndKey(libraryID, itemKey);
+			return Zotero[Types].getByLibraryAndKey(libraryID, objectKey);
 		}
 	}
 }