Davis and Sumara (2003) argue that differences between commonsense assumptions about learning and those upon which constructivism rests present a significant challenge for the fostering of constructivist approaches to teaching in schools. Indeed, as Rink (2001) suggests, initiating any change process for teaching method needs to involve some understanding of the theories supporting it. Although there has been considerable discussion about constructivism in the physical education literature over the past decade, there has been less attention paid to the assumptions about learning and knowledge that underpin it. This article makes a contribution toward redressing this oversight in the literature by examining the epistemology and assumptions about learning that constructivist theories of learning rest upon. Drawing on the work of Davis and Sumara (2003), I suggest that the term "complex" learning theories may offer a more useful description of the sometimes confusing range of constructivist approaches. I provide examples of, and suggestions for, the application of constructivism in practice and within which the body forms a prominent theme.