One could argue that attitudes, knowledge, beliefs, and differing definitions and perceptions can all affect science teachers' motivation to engage in inquiry practices. Better understanding what motivates science teachers' instructional behaviors can result in improved efforts by researchers to align their instruction with quality inquiry-based instruction. By improving the effectiveness of professional development (PD) programs, we can begin to decrease the disconnect between current teaching practice and the expectations stated in the "Next Generation Science Standards" ("NGSS"). This study seeks to determine whether Vroom's Valence-Instrumentality-Expectancy (VIE) Theory of Motivation can help explain science teachers' enactment of newly learned inquiry-based teaching practices. Specifically, the purpose of this study is to determine if Vroom's theory provides insight into teacher practice of inquiry instruction by examining teachers' ability beliefs, value of inquiry instruction, and instrumentality beliefs. Additionally, the authors were also interested to see if teachers' knowledge of inquiry instruction could be an important factor. The research questions for this study include: (1) which constructs within Vroom's VIE Theory of Motivation are related to teachers enacting quality inquiry-based instruction; and (2) how and to what extent can teachers' knowledge of inquiry instruction help explain teachers' enactment of inquiry?