ERP systems are large integrated packaged software systems used by thousands of major organizations around the world. Yet outcomes from ERP use can be very different, and there is still not an adequate understanding of how and why organizations have such varying outcomes. Using an interpretive case study approach the post implementation periods in four manufacturing companies were examined retrospectively as processes within context over time. Structuration theory was used in the analysis of the cases to identify six themes that explain ’how’ and three contexts that explain ’why’ that form the components of an explanatory framework. The framework provides a foundation for future studies to understand and explain how and why organizations have or have not achieved business benefits from ERP systems.