In government, support for strategic political steering, administrative and cross-sectoral development, and integration of processes and systems can be sought out of enterprise architecture (EA) planning. To facilitate this, a proper EA method covering essential government levels is needed. A constructive case study has been carried out to create an adaptation model of Finnish government EA (GEA) grid. The study builds on general principles of method adaptation and observations about GEA method engineering and its pilot adaptations in Finnish State Administration. The model presents systematic guidelines for situational GEA grid adaptation and reuse in Finnish State administration. The model supports GEA grid adoption as a strategic tool for planning and management of organizational change. It facilitates prioritization of government goals, communication and commitment among government actors, and implementation of government interoperability.