This report from a longitudinal study of the effects of prenatal alcohol and marijuana exposure investigates whether these drugs affect neuropsychological development at 10 years of age. Women were recruited from a medical assistance prenatal clinic and interviewed about their substance use at the end of each trimester of pregnancy, at 8 and 18 months, and at 3, 6, 10, 14, and 16 years. Half of the women were African American, and half were Caucasian. The women were generally from lower socioeconomic status families and had obtained high school degrees. At the 10-year follow-up, 593 children completed a neuropsychological battery, which focused on problem solving, learning and memory, mental flexibility, psychomotor speed, attention, and impulsivity. Prenatal alcohol use was found to have a significant negative impact on learning and memory skills, as measured by the WRAML. Prenatal marijuana exposure also had an effect on learning and memory, as well as on impulsivity, as measured by a continuous performance task. The effects of prenatal alcohol and marijuana exposure persisted when other predictors of learning and memory were controlled. We continue to follow these offspring into the adolescent years when further neuropsychological deficits may become evident.