An underexamined yet critical aspect of any theory of reflective thinking is its ontological foundations--the view of reality that it embraces. This article makes an argument that realist assumptions, such as those advanced by John Dewey, provide a basis for teacher learning superior to theories of teacher reflection resting on nonreal foundations. Dewey's theory of reflective thinking is explicated with an emphasis on his theory of reality. Implications for teacher education are discussed. (Contains 2 notes.)