Researchers in the Cognition, Learning, and Development (CLAD) Lab study cognitive development, with a primary focus on how children think, learn, and solve problems in mathematics. Because mathematical cognition follows a developmental progression that begins prior to formal schooling and continues into adulthood, participants in our studies range from preschool through college. We mainly use experimental designs to test specific, causal hypotheses about the processes involved in knowledge construction, but we also use converging evidence from longitudinal studies, structured interviews, and detailed analyses of learners’ mathematics experiences. Our goal is to answer basic questions about cognition, learning, and development while also grappling with real educational problems that parents and teachers face when making decisions about how best to present information to children in formal and informal learning environments.