This study identifies factors that are significantly related to student intentions to enter science, technology, engineering, and mathematics (STEM) occupations by age 30, and examines how those factors differ across definitions of STEM occupation, educational attainment levels, and student demographics. Data from 2009 High School Longitudinal Study base year were used, and were analyzed using multinomial logistic regression. Expectancy-value theory is the theoretical framework for this study. The findings from this study suggest that depending on the definition of STEM careers operationalized in the analysis, variation can be observed in the impact of gender, while the role of the expectancy-value constructs remains largely consistent across multiple definitions of STEM careers. The results also suggest that while expectancy-value constructs such as utility, interest, and attainment value are significantly related to the STEM career plans of White students, fewer significant relationships between expectancy-value constructs and the STEM career plans of Black and Hispanic students were identified. Additionally, findings from this study raise questions about the extent to which STEM career choices at the sub-bachelor's degree level can be understood as achievement-related choices, and thus the extent to which expectancy-value theory is a suitable framework for understanding those choices.