This study is intended to assess the changing lifestyles, values, and preferences of American youth on a continuing basis. Each year since 1975, about 17,000 seniors have participated in the survey, which is conducted in about 130 high schools nationwide. In addition, subsamples of seniors from previously participating classes receive follow-up questionnaires by mail each year. This analysis examines how work intensity (hours worked per week) is linked to indicators of psychosocial functioning and adjustment in a nationally representative sample of high school seniors from the classes of 1985-1989. Consistent with previous research, bivariate correlations were positive between work intensity and problem behaviors. However, once background and educational success indicators were controlled, theses associations were diminished. The results indicate that work intensity does contribute directly and negatively to getting sufficient sleep, eating breakfast, exercising, and having a satisfactory amount of leisure time. These findings, together with the positive association between work intensity and frequency of dating, suggest that adolescents working long hours are adopting a "harried young adult" lifestyle. It briefly discusses conceptual and policy implications, including the likelihood that long hours of part-time work are as much a symptom as a cause of psychosocial difficulties. (Contains 33 references, 3 appendixes, 29 tables, and 33 figures.) (JDM)