The present studies were conducted to investigate students' conceptions of distinct constructivist assumptions. To that end, a questionnaire was developed containing statements about four constructivist assumptions: The importance of knowledge construction, cooperative learning, self-regulation, and the use of authentic problems together with self-perceived inability to learn and motivation to learn. The studies demonstrate that the questionnaire was able to unearth students' conceptions of the distinctiveness of constructivist assumptions. Students were able to identify the six factors underlying the questionnaire, as indicated by the fit of the hypothesized model. The test for measurement invariance showed that factor loadings were equivalent across groups and that the questionnaire's underlying factor structure gave evidence of cross-validation. Testing alternative models with one and three latent factors resulted in poor model fits, supporting the questionnaire's latent factor structure. The questionnaire developed appeared an adequate instrument to investigate students' conceptions of constructivist assumptions of learning and students acknowledge the importance of these assumptions as distinct influences on their learning process. Description of the parcels with item examples (translated from Dutch) is appended. (Contains 3 figures and 6 tables.) [This research was supported by Vereniging Trustfonds Rotterdam.]