Conceptual change researchers have made significant progress on two prominent but competing theoretical perspectives regarding knowledge structure coherence. These perspectives can be broadly characterized as (1) knowledge-as-theory perspectives and (2) knowledge-as-elements perspectives. These perspectives can be briefly summarized in terms of the following questions. Is a student’s knowledge most accurately represented as a coherent unified framework of theory-like character (e.g., Carey, 1999; Chi, 2005; Ioannides & Vosniadou, 2002; Wellman & Gelman, 1992)? Or is a student’s knowledge more aptly considered as an ecology of quasi-independent elements (e.g., Clark, 2006; diSessa, Gillespie, & Esterly, 2004; Harrison, Grayson, & Treagust, 1999; Linn, Eylon, & Davis, 2004)? In this review, we clarify these two theoretical perspectives and discuss the educational implications of each. This debate is important because these perspectives implicate radically different pathways for curricular design to help students reorganize their understandings. Historically, the research literature has predominantly supported knowledge-as-theory perspectives. After outlining both perspectives, this paper discusses arguments and educational implications that potentially favor the adoption of knowledgeas- elements perspectives