There is a need for an assessment tool for evaluating the effectiveness of active learning strategies such as problem-based learning in promoting deep learning and clinical reasoning skills within the dual environments of didactic and clinical settings in health professions education. The Active Learning in Health Professions Scale (ALPHS) instrument captures three elements of active learning: activities that have elements of novel access to information, observing or participating in experiences focused on learning, and reflective practices about the learning process. In order to assess the criterion-related validity of the ALHPS, a Structural Regression Model was created in which the latent variable of Active Learning was placed as a predictor of graduating seniors' critical thinking. The strong psychometric properties of the ALHPS instrument indicate that it is possible to reliably assess students' perceptions of the frequency with which they experience active learning pedagogy within doctoral health professions education, and that such strategies are predictive directly of academic engagement and indirectly of increases in students' critical thinking skills.