Reports the results of the JOBS II randomized field experiment that included a sample of 1,801 recent job losers, 671 of which participated in a modified version of the JOBS I intervention for unemployed workers (Caplan, Vinokur, Price, & van Ryn, 1989). The intervention focused on enhancing the sense of mastery through the acquisition of job-search and problem-solving skills, and on inoculation against setbacks. JOBS II was intended to prevent poor mental health and to promote high quality reemployment. The study tested whether the efficacy of the intervention could be increased by screening and oversampling respondents who were at higher risk for a significant increase in depressive symptoms. Results demonstrated that the intervention primarily benefited the reemployment and mental health outcomes of the high-risk respondents. This suggests the feasibility of enhancing the efficacy of this preventive intervention by targeting it for high-risk unemployed workers who could be identified prospectively.