Participation of U.S. adults in formal learning activities during the 1990s was examined by analyzing data from the 1991, 1995, and 1999 Adult Education Surveys that were part of the National Household Education Surveys Program. Overall, participation in adult education between 1991 and 1999 increased among all but one age group (35-44 years), all racial/ethnic groups, all education levels, all labor force groups, and all occupation groups (except those in professional or managerial positions). The groups that did not increase their participation rates had some of the highest participation rates in 1991 and constant rates of participation thereafter. However, more in-depth statistical analyses revealed that participation in work-related courses by Hispanics, individuals with lower levels of education, individuals with lower-status jobs, and individuals who are employed part time is lower than that of other groups. Adults with lower levels of education were also less likely to participate in nonwork-related courses, even after other factors were accounted for. Despite elimination of some inequalities, highly educated and high-status groups remained the main beneficiaries of adult education. A discussion of the survey methodology and data reliability is appended along with nine standard error and logistic regression tables. (Contains 48 references and 27 tables/figures.) (MN)