While Enterprise Systems (ES) have the potential to offer benefits beyond traditional legacy systems, many organizations report that these have been less successful than originally anticipated. The difficulties of ES implementation have been widely cited in the literature but research on critical success factors (CSFs) for initial and ongoing ES implementation success is found to be fragmented. The paper presents an exploratory research study, where, particular ranked list of CSFs was first established and then used to analyze project performance in a case study of ES implementation in an airconditioning and refrigeration products industry. The CSFs identified were found to be helpful in investigating the causes for initial failure and subsequent success of the project. It was also observed that a change in attitude of top management, project management and users caused the success of the project. The study employed appropriate quantitative measures viz. statistical mean, reliability and content validity test for identification of CSFs. The case was studied using qualitative SAP-LAP (Situation-Actor-Process – Learning-Action-Performance) framework, and Causal Loop Diagramming to extend the explanatory power of CSFs in a richer framework.