||PURPOSE: The data from the National Maternal and Infant Health Survey (NMIHS) and its 3-year follow-up offer a unique opportunity to study the effects of substance (alcohol, marijuana, and tobacco) use during gestation on development at age three in a nationally representative sample. Using this data, the relationship of development (language, gross motor, fine motor, and adaptive behavior) and specific behaviors (eating problems, length of play, activity level, difficulty of management, level of happiness, fearfulness, ability to get along with peers, tantrums, eating nonfood) and maternal drinking, marijuana use, and cigarette smoking was studied in a sample of live births who had been followed up at age three. METHODS: The data were analyzed using a cumulative logit model of ordinal responses. RESULTS: Higher activity level, greater difficulty of management, tantrums, eating problems, and eating nonfood were related to maternal drinking during pregnancy. Increased fearfulness, poorer motor skills, and shorter length of play were associated with maternal marijuana use during pregnancy. Less well developed language, higher activity level, greater difficulty of management, fearfulness, decreased ability to get along with peers, and increased tantrums were associated with maternal cigarette smoking during pregnancy. The preponderance of significant effects involved the behaviors studied rather than the developmental indices. IMPLICATIONS: It may be that the effects of substance use during pregnancy, especially more subtle ones, show up in behavior before they can be measured by developmental scales.