The summer of 1985 marked the first full-scale implementation of the Summer Training and Education Program (STEP) model. Federally funded, STEP provides 14- and 15-year-olds with a paid summer experience that combines work, remediation in reading and math, and life skills instruction with an emphasis on responsible social and sexual attitudes and behavior. Participants spend two consecutive summers in the program. The first cohort consisted of 1,592 youths (each receiving $3.35 per hour). They were randomly assigned to treatment and control groups at five demonstration sites--Boston, Fresno, San Diego, Seattle, and Portland, Oregon. In the posttest, the youths in the treatment group outscored their control group counterparts in both reading and math by approximately one quarter of a grade equivalent. The impact of participation varied as a function of sex, race, and site. Girls in the treatment group showed greater reading gains over their counterparts in the control group than did the boys. Sex was not as great a factor in the math scores, however. Hispanic youths showed the greatest gains, with Asians and Blacks deriving solid benefits as well. The impact of participation varied among the sites, with the most impact occurring in Boston and the least occurring in Portland. The program also appeared to result in changes in self-reported sexual behavior of boys, an effect unusual among pregnancy prevention programs. (Appendixes include technical data tables and discussions of the test floor effect, attrition, and control group losses.) (MN)