This paper provides a description of fifty-five ERP Project Retrospectives. The study uses the ERP project retrospectives to shed light on relevant issues identified in the literature review of ERP research conducted over the past decade (Schlicher and Kraemmergaard, 2010). The retrospectives provide insight into a number of key questions, including: (1) project justification, including the business and system benefits of ERP; (2) lessons learned, including common mistakes, challenges met, and best practices in managing these challenges; (3) and critical success factors in implementation. The study describes the similarities and differences between the literature and the walkthroughs.