The successful implementation of Enterprise Resource Planning (ERP) system is a challenge to many organizations. Though an intervention, ERP brings in large scale tangible and intangible benefits to an organization. It poses significant intervention on firm level endogenous dimensions; internal stakeholders, internal organization, business processes and technology. Though literature recognizes that ERP intervention brings about technological change during ERP implementation, hardly any article has conceptualized these interventions in evaluating its performance. Drawing on the Socio Technical system perspective the objective of this article is to conceptualize the ERP intervention on the endogenous dimensions of the organization and develop a comprehensive conceptual model to assess the success or failure of ERP system implementation. The conceptual model, Process-Variance and Adapted Socio-Technical (PVAST), proposed in this article will enable decision makers and practitioners to measure ERP project performance at every stage of its life cycle in a coherent method and adopt corrective measures.