Recent advances in the discipline of developmental psychopathology highlight the contributions of developmental thought to the study of persons with autism. This article briefly outlines primary developmental innovations in theory, methodology, and the interpretation of findings. Specifically, we discuss two sets of issues that arise from the general notion of developmental level. One set is relevant to the choice of persons that comprise the comparison group and the other to the various implications of the subjects' levels of functioning. In sum, we contend that researchers need to frame their empirical work within the context of developmental theory and methodology and interpret their findings accordingly. This will lead to scientifically compelling work and an increasingly heuristic approach to the study of persons with autism.