This paper examines effects of life-skills, mentoring, and counseling education intervention implemented among primary school attending girls aged between 10 and 19 years, living in Nairobi slums. We hypothesized that interaction between the intervention and aspiration, self-confidence and interest in schooling, mediates the impact of risky behavior on academic performance. This quasi-experimental study had two treatment arms of 538 girls and one comparison with 272 girls. The first treatment arm received life skills mentoring, after school support with homework, and parental counseling; the second treatment arm received a package similar to the first arm excluding parental counseling; while the comparison arm received nothing during the implementation period, but they got a secondary school fees subsidy at the end of the intervention. The analysis shows that the intervention had statistically significant effects on some aspects of risky behavior and the mediators. Results from a structural equation model show existence of strong moderated mediation effects of risky behavior on academic performance. The importance of the findings is in demonstrating how inner-character attributes could enhance learning outcomes, especially among adolescent girls in low-resourced environments.