Using a data sample from the National Longitudinal Survey of Youth that included all youths enrolled in high school who were aged 16-19 in 1979, a study tracked the youths' labor force attachment and earnings 12 years later. The study found that students who worked while in high school show increased rates of labor force participation along with lower rates of unemployment 12 years later. At the later date, of those with the heaviest work schedules while in school, 87 percent were employed and only 4 percent were unemployed (the rest were not in the labor force). Those with moderate work hours while in school had an 81 percent employment rate and 5 percent unemployment rate 12 years later, whereas of those with no work hours while in school 72 percent were employed and 7 percent were unemployed. In addition, those who had the heaviest work schedules while in high school had the highest earnings in the later study---attributable to more hours worked per year. The study also found that the teens who were most likely to work had higher family incomes, better-educated parents, and more often, two working parents in the home. When differences in family background were accounted for, the only potentially negative effect of in-school work is that those who worked, especially those who worked the most hours, tended to complete about 12 weeks less total education than did students who did not work while in school. The study concluded that the measured reduction in adult unemployment rates of those teens who worked speaks to the importance and value of the work they carried out. Their reduced unemployment rates, greater labor force attachment, and earnings gains all took place despite the fact that the typical employment opportunities were found in the service and retail sectors, jobs often maligned in discussions of the current economy. (Contains 22 references.) (KC)