Constructivism is defined in a variety of ways (e.g., constructivist research paradigm, sociological constructivism, and philosophical constructivism) and applied in vastly different contexts. Among the various usages and interpretations of constructivism, one is educational constructivism that embodies an epistemological view of knowledge and learning that is an alternative to naive empiricism or classical behaviorism. To represent the full range of stances taken by educational constructivists, three versions of educational constructivism were considered in this study: individual constructivism originating in the work of Piaget, the radical version of constructivism associated with von Glasersfeld, and the social constructivism of Vygotsky. I investigated preservice teachers' meaning construction about constructivist epistemology as they went through their preservice teacher education program using in-depth interviews. This preservice teacher education program employs constructivist aspects of teacher education and generates applications of constructivism to the practice of teaching. Features of preservice teachers' internalized meanings of educational constructivism include: (1)traditional pedagogy as the default, (2) Literal interpretation of constructivism, (3) Individual constructivism as conceptual change learning, (4) Radical constructivism as a strong individualistic philosophy, (5) Social constructivism as being too ideal to be practical. A compilation of the teachers' own statements about how to implement conceptual change learning and their projected role as constructivist teacher is also provided.