Implementing an Enterprise Resource Planning (ERP) system project is a difficult and high cost proposition as it places tremendous demands on organization's time and resources. The ERP implementation literature contains many case studies of organizations that have implemented ERP systems successfully. However, many organizations do not achieve success in their ERP implementation projects. Much has been written about implementation and the critical success factors for ERP implementation projects. But there very few studies have scientifically developed and tested constructs that represent ERP implementation process stages and ERP success. Based on a survey of 53 organizations in Australia, the results suggest that a 20 item instrument that measures seven dimensions of ERP implementation process stages is well - validated. It is found that the respondents perceive that all the implementation stages in the study propose are important to achieve success in ERP implementation. However, the implementation planning and installation are found to be statistically significant for the success of ERP implementation project. The results presented in this study are valuable to researchers and practitioners interested in implementing Enterprise Resource Planning systems.