In this study, the relationship between students' interest in engineering design activities and their expectancy for success in grades 9-12 was evaluated. The theoretical frameworks developed by Eccles and colleagues (i.e., expectancy value) and Butler and Cartier (i.e., what the students bring to contexts under a self-regulated learning framework) were used to frame the relationship between students' interest and expectancy for success. Specifically, this study extends the value part with interest by using psychological constructs of the Motivated Strategies for Learning Questionnaire (MSLQ). Three psychological constructs were used to evaluate students' interest: intrinsic goal orientation (IGO), extrinsic goal orientation (EGO), and task value (TV). Two other psychological constructs were used to evaluate students' expectancy for success in completing the design tasks: control of learning beliefs (CLB) and self-efficacy for learning and performance (SELP). A total of 113 students participated in the study. These students participated in five schools (in three states) that implement the Project Lead the Way curriculum. After finishing their design project, each student was asked to complete a modified version of the MSLQ survey instrument that evaluated the five aforementioned constructs. From a statistical test, it was found that there was a significant relationship between students' interest in the engineering design tasks and their expectancy for success. Further statistical tests also indicated significant relationships between each construct of the interest and expectancy components. From a regression test, it was found that students' intrinsic goal orientation and task value were significant predictors, each contributing about 55 and 34 percent, respectively, to students' expectancy for success. (Contains 6 tables and 1 figure.)