Longitudinal evaluation of interprofessional programming is necessary to understand the impact of interprofessional education (IPE) for collaborative practice. Attitude is one measure of intended behavior. The Interprofessional Attitude Scale (IPAS) was developed as an improved measure to examine the readiness for interprofessional education and collaborative practice. As a means to pilot a protocol for a longitudinal comprehensive evaluation of an interprofessional program with 13 health professional programs in 6 health science faculties, the IPAS was administered over a 3-year period to three cohorts of students. The results of the IPAS indicated no significant differences detected across the 3 years. Although there was a significant difference on the Patient Centredness subscale for Cohorts 2 and 3 the effect size was small. Previous experience in an interprofessional course was a predictor of more positive patient centeredness attitudes, but other IPE experience and years of education were not predictors of any interprofessional attitudes. Students from the Medicine & Dentistry (M&D) faculty ranked significantly lower on the teamwork roles and responsibilities subscale compared to the other faculties, except Rehabilitation Medicine (RM). However, once the outliers in RM were removed, there was a significant difference on this subscale between RM and M&D. This paper outlines the challenges with using the IPAS as part of a comprehensive program evaluation and identifies issues with longitudinal data collection for evaluation with large student cohorts.