As medical schools have changed their curricula to address foundational and clinical sciences in a more integrated fashion, teaching methods such as concept mapping have been incorporated in small group learning settings. Methods that can assess students' ability to apply such integrated knowledge are not as developed, however. The purpose of this project was to assess the validity of scores on a focused version of concept maps called mechanistic case diagrams (MCDs), which are hypothesized to enhance existing tools for assessing integrated knowledge that supports clinical reasoning. The data were from the medical school graduating class of 2018 (N = 136 students). In 2014-2015 we implemented a total of 16 case diagrams in case analysis groups within the Mechanisms of Health and Disease (MOHD) strand of the pre-clinical curriculum. These cases were based on topics being taught during the lectures and small group sessions for MOHD. We created an overall score across all 16 cases for each student. We then correlated these scores with performance in the preclinical curriculum [as assessed by overall performance in MOHD integrated foundational basic science courses and overall performance in the Clinical and Professional Skills (CAPS) courses], and standardized licensing exam scores [United States Medical Licensing Exam (USMLE)] Step 1 (following core clerkships) and Step 2 Clinical Knowledge (at the beginning of the fourth year of medical school). MCD scores correlated with students' overall basic science scores (r = 0.46, p = 0.0002) and their overall performance in Clinical and Professional Skills courses (r = 0.49, p < 0.0001). In addition, they correlated significantly with standardized exam measures, including USMLE Step 1 (r = 0.33, p [less than or equal to] 0.0001), and USMLE Step 2 CK (r = 0.39, p < 0.0001). These results provide preliminary validity evidence that MCDs may be useful in identifying students who have difficulty in integrating foundational and clinical sciences.