This publication provides a holistic approach to evaluate progress in the development of a nuclear power infrastructure based on the guidance contained in IAEA Nuclear Energy Series No. NG-G-3.1, Milestones in the Development of a National Infrastructure for Nuclear Power. It is intended to support Member States in their progress evaluation, or as a basis for an IAEA Integrated Nuclear Infrastructure Review (INIR) mission. While Phases 1 and 2 of nuclear power infrastructure development are contained in the previous editions, evaluation methodology and conditions for Phase 3 have been added to this revision, using the feedback and lessons learned from its application in two pilot INIR Phase 3 missions.