In this study, the different types of research designs used to assess the impact of prerequisite courses are presented. Supported by an in-depth literature review, the challenges that are faced in the assessment of the impact of prerequisites, from statistical to political, are identified and their pitfalls are pointed out. In particular, the challenges inherent in the use of quantitative methods--the preferred method in assessing the impact of prerequisites--are presented and discussed. In light of these challenges, the inference is made that efforts to validate prerequisites before they are established should replace efforts to assess their impact once they have been established. New trends to validate prerequisites based on novel identification and design paradigms are identified.