Jonas indicated that educators interpret/apply concepts of interest differently. Dewey, following the different ways that teachers apply concepts of student interest, categorized teachers as advocates of efforts and as advocates of autonomy. Renninger and Heidi claimed that the greatest defect in the psychology of learning is the lack of an adequate theory of interest. Together, Dewey, Jonas, and Renninger and Heidi claim that a scientific theory of interest has yet to be developed. Despite the importance of and the need to understand the place of student interest in teaching practices, a theory on students' interest is still unclear because many articles ask the wrong research questions. Specifically, Krapp and Renninger and Heidi emphasized that research on interest does not reflect a shared view of interest. Educational researchers and practitioners define and apply concepts of interest differently; they do not develop or operate with shared views of students' interest or engage one another in learning about students' interest or in learning to help students develop interest in learning. Using the phenomenological method, the purpose of this study is to evaluate the leading theories of student interest and develop a theory that explains how concepts of student interest relate to performance. Findings from this study are intended to help teachers develop an increased understanding of the concepts of student interest and to help students learn optimally.