Risk and protective factors of the family and individual microsystems associated with early sexual intercourse among a sample of low-income adolescents were assessed using bioecological theory in combination with a risk and resiliency framework. The risk factors examined were adolescent race, gender, family structure, low maternal education, family welfare receipt, income, and delinquent behaviors. Protective factors explored included family routines, parental monitoring, parent-child relationships, father involvement, academic achievement and academic aspirations. Waves 1 and 2 of the Welfare, Children and Families: A Three-City Study were used (N=984, ages 10 to 14 years). Relationships between early sexual activity and sexual debut with family and individual risk and protective factors were assessed using a series of logistic regressions. Overall findings show that age, gender, race, living in a two-parent family, a separated family, a family where the mother formed a union between waves, transitioning on welfare between waves, and being involved in delinquent acts significantly increases the odds that adolescents will be sexually active. Protective factors for early sexual activity include living with a mother who has a technical degree or higher, living with a mother who increased her education between waves, and father involvement. Risk factors for early sexual debut were age, gender, race, living in a two-parent family, living in a separated family, and delinquent involvement. The only protective factor for early sexual debut was maternal education. Findings differed by gender, race, and race*gender. Policy implications include increasing social and human capital among low-income mothers to promote family stability and providing diversified sexual education programs due to gender differences. With an average age of 12.8 years among adolescents who were sexually active, prevention programs need to be implemented earlier in school; implementation in elementary school is warranted.