This paper explores three research issues on adolescent development using an elaborated effects model: (1) Are there consistent sex main effects on a variety of student outcomes? (2) What are the relative influences of family status, family processes, school processes, and individual ability on academic and nonacademic behavior of males and females? and (3) Do the same influence processes operate for males and females or are there important sex interaction effects with family or school characteristics? The study utilizes survey data from 4,079 white students in 10 middle schools and six high schools in Maryland that differ significantly in authority structure. The sample of students from grades 6, 7, 9 and 12 is diverse in social and family processes. Results show: (1) significant sex main effects of five outcomes--self esteem, college plans, academic subject preference, adjustment in school and report card grades; (2) clear differences in patterns of influence of variables--family and school processes are more important for personality and school coping skills, and family status and individual ability are more important for college plans and standardized achievement; and (3) no consistent, significant sex interactions. (Author/MFD)