Abstract: Purpose – The purpose of this paper is to explore the critical success factors (CSFs) of enterprise resource planning (ERP) system implementation in small and medium-sized enterprises (SMEs). Design/methodology/approach – Five case studies of Canadian SMEs were conducted. They included interviewing individuals from five roles at each organization and gathering project documents. Following an evaluation of each project's success (within-case analysis), cross-case analysis was conducted to elicit influential and distinctive factors. Findings – Factors were identified that appeared to explain variation between successful and unsuccessful implementations at SMEs, besides factors that appeared to be innovative or counter-intuitive in light of the established literature. Research limitations/implications – The study reinforces the need for more research that is focused on SMEs. All cases were of Canadian SMEs with either a manufacturing or distribution focus, potentially limiting the generalizability of findings to other industries or countries. Practical implications – By identifying relevant CSFs for SMEs, managers can better prioritize implementation efforts and resources to maximize success of ERP implementations. Originality/value – The paper appears to be one of the first studies to focus on the CSFs of ERP implementation at SMEs.