This study is one of the "knowledge development" activities mounted in conjunction with research, evaluation, and development activities funded under the Youth Employment and Demonstration Projects Act of 1977 (YEDPA). It focuses on the impacts of Job Corps participation on a large group of participants after 18 months to two years. Significant benefits are documented, benefits which exceed the costs to society of the investment in Job Corps. Material covered in the study includes an overview of the Job Corps and the evaluation; overall impacts on employment and related activities; changes in family composition and employment-related impacts for females with children; comparison of benefits and cost; analysis of differential factors among participants and centers; analysis of program expenditures; and generalizability of the findings. (KC)