Direct language instruction and interactive language instruction are based on highly distinct theoretical positions and incorporate very different behavioral techniques. A purpose of the present study was to evaluate the relative effectiveness of direct and interactive language instruction in promoting a variety of language skills. A second purpose was to determine if an aptitude and treatment interaction influenced the outcome of intervention. Forty-four children of preschool age were randomly assigned to classrooms using either direct instruction or interactive instruction. After 8 months, children in both settings improved significantly and substantially on syntactic and semantic measures. There were no differences between the two groups at posttest, nor were there any significant aptitude by treatment interactions for either cognitive or language pretest measures. The results of this study, and a careful examination of previously reported interactions, suggest that such an interaction has yet to be demonstrated.