This longitudinal study investigated development in expectancy for success (perceived competence), 3 types of task value (utility, interest, attainment), and 3 types of perceived cost (opportunity, effort, psychological) for engineering students during their first 2 years of college. Latent growth curve models indicated declines in expectancy and values, with attainment value declining more slowly than expectancy, interest value, and utility value. Costs increased over time, with effort cost increasing more rapidly than psychological cost. Demographic differences were observed in initial levels of motivation, but not in rates of change over time. Students with slower declines in expectancy and value and slower increases in effort cost achieved higher grades and were more likely to remain in an engineering major. The attainment value model explained the largest amount of variance in engineering major retention, while the expectancy model explained the largest amount of variance in GPA. Taking a supportive gateway course in the first semester rather than later was associated with slower declines in utility value and attainment value, and slower increases in effort cost. Results suggest expectancy, values, and costs display unique patterns of development and uniquely relate to predictors and outcomes, extending our theoretical understanding of motivation in early college. Implications for practice include the promise of programmatic efforts to support students' motivation in engineering through supportive gateway courses early in college. Educational Impact and Implications Statement Motivation processes provide a promising avenue for addressing attrition and representation issues in STEM fields. Yet, little is known about the development of specific forms of motivation and their correlates during the first 2 years of college, a key time for shaping motivational beliefs and future choices. Among college engineering students, positive motivational beliefs (expectancy for success, interest value, attainment value, and utility value) regarding engineering declined over time while negative motivational beliefs (perceived opportunity cost, effort cost, and psychological cost) increased over time. Differential rates of change for each motivation construct suggest that developmental processes differ across motivational constructs. Women did not report different trajectories than men; however, underrepresented minority students and first-generation college students reported more adaptive patterns of motivation when beginning college. Developmental trajectories of motivation constructs were significantly related to retention and grades, with expectancy most strongly predicting grades and identity-related attainment value most strongly predicting major retention. Lastly, students enrolled in a supportive gateway course in their first semester (vs. later) exhibited slower declines in attainment and utility value, and slower increases in effort cost. Results highlight the importance of supporting college students' motivation in STEM fields and of the key role of supportive gateway courses. Furthermore, differences in developmental trajectories and their relations to predictors highlight the need to understand students' specific motivational needs. Results also suggest implications for the timing and design of motivational interventions to support college student success in STEM.