A large body of literature exists describing the harmful effects of prenatal drug exposure on infant and child development. However, there is a paucity of research examining strategies to ameliorate sequelae such as externalizing behavior problems. In the present study, functional analysis procedures were used to assess challenging behavior exhibited by two children who were prenatally exposed to drugs of abuse. Results for both children indicated that challenging behavior was maintained by access to positive reinforcement (adult attention and tangible items). For one child, challenging behavior was also maintained by negative reinforcement (escape from activities of daily living). Function-based interventions were effective in reducing challenging behavior for both children. Implications for utilizing methods of applied behavior analysis in research with children with prenatal drug exposure are discussed. (Contains 3 figures.)