Student-survey, teacher-report, and achievement-test data were collected from students when those normally progressing entered grade 5 and again when they completed grade 6. For these analyses, students were divided into two conditions: control groups (students who received no intervention during grades 6) and full intervention group (students exposed to at least one semester of the intervention in grades 1 to 4 and at least one semester of intervention in grades 5 to 6). The low-income sample had 106 students (58 percent control and 42 percent intervention). Analyses compared the low-income intervention and control groups on measures of the social development model construct (classroom and family opportunities, skills, reinforcements, and levels of bonding) and outcome measures (norms against substance use, drug and delinquency initiation). Findings show that intervention girls perceived more opportunities and reinforcements for classroom involvement and expressed stronger school bonding in both the attachment and commitment dimensions. The intervention girls were less likely to have smoked tobacco and somewhat less likely to have initiated alcohol or marijuana use. Intervention boys were significantly more socially competent and had better schoolwork skills than control boys. Although the findings support the potential of comprehensive school-based strategies in affecting children from low-income families, the small number of low-income students available for outcome analysis suggests caution in generalizing from these results. 2 tables