Interim estimates were made of program impacts on earnings and employment of adults and out-of-school youths during the first 18 months after their acceptance into employment and training programs funded under Title IIA of the Job Training Partnership Act (JTPA). In the national study, 20,601 JTPA applicants in 16 service delivery areas were randomly assigned to treatment (allowed access to the program) or control groups. Analysis was based on a subsample of 17,026 participants interviewed 18 months after assignment. Different service strategies (classroom training, on-the-job training/job search assistance, and other services) were used for four subgroups: adult men, adult women, out-of-school male youths, and out-of-school female youths. Findings included the following: (1) Title IIA had generally positive effects on employment and earnings of adults in the treatment group; (2) it had little or no effect on average earnings of female youths, actually reduced earnings of male youths, and had no significant effect on youth employment rates; (3) almost all the negative impact on male youths' earnings was among those who had been arrested between age 16 and random assignment (25% of the subgroup); (4) earnings impacts reflected amount of time worked and how much was earned per hour; and (5) sites did not differ significantly in degree of effect on earnings. It was concluded that JTPA Title IIA is helping raise the earnings of many participants, especially adults. It is possible that adult/youth differences are the result of age alone. Ways to improve program effects for those groups negligibly or adversely affected by the program will require experimentation with a range of alternative service strategies and rigorous evaluation of their impacts. (Appendices contain the following: comparison of study sample with nationwide Title IIA participants; comparison of baseline characteristics of treatment and control groups; data sources; sample definition and impact evaluation method; comparison of data from first follow-up survey and state unemployment insurance agencies; analysis of nonenrollees; estimation of impacts on latent wage rates; and exhibits on out-of-school youth. There are 67 references and 156 data tables.) (YLB)