diff --git a/collects/scribble/base-render.rkt b/collects/scribble/base-render.rkt
index f0241ffe..ed76353a 100644
--- a/collects/scribble/base-render.rkt
+++ b/collects/scribble/base-render.rkt
@@ -72,7 +72,8 @@
 
     (define/public (format-number number sep)
       (if (or (null? number)
-              (andmap not number)
+              (andmap (lambda (x) (or (not x) (equal? x "")))
+                      number)
               (and (not (car number))
                    (not (ormap number? number))))
           null
@@ -81,7 +82,10 @@
                            string-append
                            (map (lambda (n) (if (number? n) (format "~a." n) ""))
                                 (reverse (cdr number))))
-                          (if (car number) (format "~a." (car number)) ""))])
+                          (if (and (car number) 
+                                   (not (equal? "" (car number))))
+                              (format "~a." (car number)) 
+                              ""))])
                   (substring s 0 (sub1 (string-length s))))
                 sep)))
 
@@ -520,7 +524,9 @@
                     (define next-sub-pos
                       (collect-part s d p-ci
                                     (cons (if hidden-number?
-                                              #f 
+                                              (if sub-grouper?
+                                                  ""
+                                                  #f)
                                               (if sub-grouper?
                                                   (number->roman pos)
                                                   pos))
@@ -972,9 +978,8 @@
                                    (not (= base-len (sub1 (length number))))))
                        (positive? depth))
                   (apply append (map (lambda (p)
-                                       (if (part-style? p 'toc-hidden)
-                                           null
-                                           (generate-toc p ri base-len #f quiet (sub1 depth) prefixes)))
+                                       (generate-toc p ri base-len (part-style? p 'toc-hidden) 
+                                                     quiet (sub1 depth) prefixes))
                                      (part-parts part)))
                   null)])
         (if skip?
diff --git a/collects/scribble/html-render.rkt b/collects/scribble/html-render.rkt
index 3976cd66..6d89789c 100644
--- a/collects/scribble/html-render.rkt
+++ b/collects/scribble/html-render.rkt
@@ -517,10 +517,22 @@
     (define/public (nearly-top? d ri top)
       #f)
 
+    (define hidden-memo (make-weak-hasheq))
+    (define/public (all-toc-hidden? p)
+      (hash-ref hidden-memo
+                p
+                (lambda ()
+                  (define h? (and (part-style? p 'toc-hidden)
+                                  (andmap (lambda (s) (all-toc-hidden? s))
+                                          (part-parts p))))
+                  (hash-set! hidden-memo p h?)
+                  h?)))
+
     (define/private (render-onthispage-contents d ri top box-class sections-in-toc?)
-      (if (ormap (lambda (p) (or (part-whole-page? p ri)
-                                 (part-style? p 'toc-hidden)))
-                 (part-parts d))
+      (if (andmap (lambda (p) (or (part-whole-page? p ri)
+                                  (and (part-style? p 'toc-hidden)
+                                       (all-toc-hidden? p))))
+                  (part-parts d))
         null
         (let ([nearly-top? (lambda (d) 
                              ;; If ToC would be collapsed, then 
@@ -560,18 +572,22 @@
              (table-blockss table)))
           (define ps
             ((if (nearly-top? d) values cdr)
-             (let flatten ([d d][prefixes null][top? #t])
+             (let flatten ([d d] [prefixes null] [top? #t])
                (let ([prefixes (if (and (not top?) (part-tag-prefix d))
                                    (cons (part-tag-prefix d) prefixes)
                                    prefixes)])
                  (append*
                   ;; don't include the section if it's in the TOC
-                  (if (nearly-top? d) null (list (cons d prefixes)))
+                  (if (or (nearly-top? d) 
+                          (part-style? d 'toc-hidden))
+                      null 
+                      (list (cons d prefixes)))
                   ;; get internal targets:
                   (map (lambda (v) (cons v prefixes)) (append-map block-targets (part-blocks d)))
                   (map (lambda (p) (if (or (part-whole-page? p ri) 
-                                           (part-style? p 'toc-hidden))
-                                       null 
+                                           (and (part-style? p 'toc-hidden)
+                                                (all-toc-hidden? p)))
+                                       null
                                        (flatten p prefixes #f)))
                        (part-parts d)))))))
           (define any-parts? (ormap (compose part? car) ps))
@@ -1464,7 +1480,8 @@
              part-whole-page?
              format-number
              install-extra-files
-             report-output?)
+             report-output?
+             all-toc-hidden?)
 
     (define/override (get-suffix) #"")
 
diff --git a/collects/scribble/latex-render.rkt b/collects/scribble/latex-render.rkt
index 4c39f9bd..196946e0 100644
--- a/collects/scribble/latex-render.rkt
+++ b/collects/scribble/latex-render.rkt
@@ -166,6 +166,7 @@
            [else
             (define no-number? (and (pair? number) 
                                     (or (not (car number))
+                                        (equal? "" (car number))
                                         ((length number) . > . 3))))
             (define no-toc? (part-style? d 'toc-hidden))
             (define (show-number)
diff --git a/collects/scribblings/scribble/core.scrbl b/collects/scribblings/scribble/core.scrbl
index 0594cdf6..09e7f8d4 100644
--- a/collects/scribblings/scribble/core.scrbl
+++ b/collects/scribblings/scribble/core.scrbl
@@ -1016,9 +1016,10 @@ Computed for each part by the @techlink{collect pass}.
 
 The length of the @racket[number] list indicates the section's nesting
 depth.  Numbers in @racket[number] correspond to the section's number,
-it's parent's number, etc. A string is used for a @racket['grouping]
-section, and @racket[#f] is used in place of all numbers for an
-unnumbered section.}
+it's parent's number, etc. A non-empty string is used for a
+@racket['grouping] section. For an unnumbered section, @racket[#f] is
+used in place of all numbers and @racket[""] in place of all non-empty
+strings.}
 
 
 @defstruct[target-url ([addr path-string?])]{