I know that this was an important art movement but Im not sure of the
artists involved in the United States and in Mexico and also when this
movement started and how long it lasted.  Can you tell me where to
find more accurate information on this movement, as well its style and
the artists involved?

These three links should be very helpful. They list how the movement
started, when it started, and the first link lists many of the artists
involved in the movement:

http://www.artcyclopedia.com/history/social-realism.html

http://www.samuseum.org/laac/laac_cd/INT_ETC/GLOSSAR2.HTM#SOCI

http://www.samuseum.org/laac/laac_cd/MODERN/VANGUARD/6B1.HTM

Hope this helps.

thanks for your help - I actually had one of those links already - I
have to write a three page paper and the the text doesn't give me much
information at all....so I guess this will have to do.  Thanks!

Perhaps these links may be of help to you.

http://dir.yahoo.com/Arts/Art_History/Periods_and_Movements/Social_Realism/Artists/

http://www.artincontext.org/listings/artist/genre/socialra.htm

http://www.ugapress.uga.edu/books/shelf/0820325643.html

http://www.artnet.com/library/07/0794/T079466.ASP