One approach to understanding model-based reasoning in science is to examine how it develops during infancy, childhood, and adolescence. The way in which thinking changes sometimes provides clues to its nature. This paper examines cognitive developmental aspects of modeling practices and discusses how a developmental perspective can enrich the study of model-based scientific reasoning in adults. The paper begins with issues concerning developmental change, followed by a model of model-based reasoning. The rest of the paper describes how several key concepts (...) from recent developmental work could contribute to current work on model-based reasoning. Specifically, developmental research shows that (a) social processes are involved in model-based reasoning and scientific discovery, (b) the development of a theory of mind contributes to the development of scientific reasoning, (c) changes in scientific reasoning are characterized by cognitive variability, and (d) microgenetic methods could clarify conceptual change during model-based reasoning. (shrink)