Hi Steven,
Here's a macro that will do it if the datasource is a table in a Word
document. If it isn't you can use a directory or catalog type mailmerge to
create such a datasource:
' Macro to assign numbers to data source so that it can be sorted to cause
labels to print down columns
Dim Message, Title, Default, labelrows, labelcolumns, i As Integer, j As
Integer, k As Integer
Message = "Enter the number of labels in a row" ' Set prompt.
Title = "Labels per Row" ' Set title.
Default = "3" ' Set default.
' Display message, title, and default value.
labelcolumns = InputBox(Message, Title, Default)
Message = "Enter the number of labels in a column" ' Set prompt.
Title = "Labels per column" ' Set title.
Default = "5" ' Set default.
labelrows = InputBox(Message, Title, Default)
ActiveDocument.Tables(1).Columns.Add
BeforeColumn:=ActiveDocument.Tables(1).Columns(1)
ActiveDocument.Tables(1).Rows(1).Range.Cut
k = 1
For i = 1 To ActiveDocument.Tables(1).Rows.Count - labelcolumns
For j = 1 To labelrows
ActiveDocument.Tables(1).Cell(i, 1).Range.InsertBefore k + (j - 1) *
labelcolumns
i = i + 1
Next j
k = k + 1
i = i - 1
If k Mod labelcolumns = 1 Then k = k - labelcolumns + labelcolumns *
labelrows
Next i
ActiveDocument.Tables(1).Sort FieldNumber:="Column 1"
ActiveDocument.Tables(1).Rows(1).Select
Selection.Paste
ActiveDocument.Tables(1).Columns(1).Delete

Signature
Please post any further questions or followup to the newsgroups for the
benefit of others who may be interested. Unsolicited questions forwarded
directly to me will only be answered on a paid consulting basis.
Hope this helps
Doug Robbins - Word MVP
> I am performing a mail merge in MSWord XP and want the data to be
> sorted down the columns, not across the rows.
[quoted text clipped - 14 lines]
> Is there a way to tell Word to organize the data this way? It is much
> more efficient when it comes down to finally labelling the envelopes.