Is it possible to take 4, ¼ page PDFs and combine them into a single
full-page pdf using acrobat 6.0 Standard? How?

Basically, we have received four ¼ page adds as pdfs and want to
combine them into a single page ad. Please note that we do not have
other graphics software.

Sure, it's possible.  First, I am assuming that you have the full
version of Acrobat, as opposed to just the Reader.  Also, are the
smaller ads 1/4 page but actually on letter-sized PDF pages?  If so,
here's what to do.

Use the "TouchUp Object Tool," which looks like an arrow.  Click and
drag a box around everything in the first PDF file and move it to the
upper left corner of the page to make room for the other 3 ads (you
can either use the mouse, or the arrow keys, which are slower but may
help your placement be more precise).  Open file #2 and use this tool
to select the content of the second ad.  Click Edit>Copy.  Switching
back to the first file, click Edit>Paste, then move to the upper right
hand corner.  Repeat this with the remaining 2 files.  Then "Save As"
a new file.

If the page size of the original 4 PDFs is actually a quarter-page,
you can create a blank PDF (from Word or elsewhere) and then paste all
4 ads into it.

Does this help?  I hope so.  Otherwise, there may be some other work-arounds.

Let me give this a try over the weekend. We had major problems last
year, but were using Acrobat 4.0 (just upgraded to 6.0). If it is this
simple, I feel a bit stupid (OK, really stupid!).

The pages usually come in as actually 1/4 page size, but occasionally
as the other (1/4 page on a full page). I can see how your
instructions would work for either. Thank a WHOLE LOT! I'll repost on
Monday to tell you if we got this to work. -Susan