This document proposes a Systems Integration Process Model (SIPM) to address integration challenges across the system lifecycle. It describes a Systems Integration Framework (SIF) developed by the authors that incorporates integration aspects from start to finish. The framework identifies five key process areas for systems integration: interoperability, requirements management, interface control, testing/validation, and legacy/COTS integration. It argues an end-to-end approach is needed to minimize later integration issues. The SIPM was tested on a government agency to evaluate its integration processes and provide recommendations.