Design is widely recognized as a central topic in engineering education, but we are only beginning to understand student conceptions of engineering design. Based on two survey data sets from the Center for the Advancement for Engineering Education's Academic Pathways Study (APS), we provide a quantitative characterization of how student conceptions of engineering design change during the course of four years of undergraduate study, as well as a gender comparison of first-year conceptions of engineering design. As a secondary contribution, we discuss the two APS data sets as a case study in the methodological trade-offs between longitudinal and cross-sectional research designs. We found remarkable alignment between the two data sets, in spite of differences in data collection-one collected longitudinally and the other, cross-sectionally. The paper closes by discussing next analysis steps, as well as potential implications of our findings on how we educate undergraduate engineers.