To address the seven guiding questions posed for authors of articles in this special issue, we begin by discussing the development (in the late 1970s-early 1980s) of Eccles' expectancy-value theory of achievement choice (EEVT), a theory developed to explain the cultural phenomenon of why girls were less likely to participate in STEM courses and careers. We then discuss how we tested key predictions from the theory, notably how expectancies and values relate to achievement choices and performance and how socialization practices at home and in school influence them. Next, we discuss three main refinements: addressing developmental aspects of the theory, refining construct definitions, and renaming the theory "situated" expectancy value theory. We discuss reasons for that change, and their implications. To illustrate the theory's practicality, we discuss intervention projects based in the model, and what next steps should be in SEVT-based intervention research. We close with suggestions for future research, emphasizing attaining consensus on how to measure the central constructs, expanding the model to capture better motivation of diverse groups, and the challenges of testing the increasingly complex predictions stemming from the model. Throughout the manuscript, we make suggestions for early career researchers to provide guidance for their own development of theories.