This guide provides basic information for members of minority groups who wish to participate effectively in the reapportionment that will take place as a result of the 1990 Census. The guide focuses on Blacks and Hispanics--the largest minority groups and the only ones for which there are reliable population figures that are more recent than the 1980 Census. The guide contains the following sections: (1) "Introduction: The 1990 Census and Political Power for Minorities" by William P. O'Hare; (2) "Demographic Change in the Black Population" by William P. O'Hare; (3) "Blacks, the Changing Political Climate, and Redistricting" by Linda Willaims; (4) "Latino Representation and the 1990 Census" by Robert Brischetto; (5) "The Changing Hispanic Political Landscape" by Rodolfo O. de la Garza and Louis De Sipio; (6) "Changing Standards in Voting Rights Law" by Frank R. Parker; (7) "The Impact of New Technology and New Census Data on Redistricting in the 1990s" by Carlton Henry; (8) "Redistricting Resources for Minority Groups" by Taynia Mann; (9) "References"; and (10) "Notes on Contributors." (DM)