Nuclear safety capacity building depends on self-assessed needs analysis for education, training, human resources, knowledge management, and networks. This publication aims to guide Member States in fulfilling the IAEA Safety Standards requirements for capacity building in nuclear safety. It emphasizes a comprehensive approach based on self-assessed needs analysis, covering education and training (E&T), human resource development (HRD), knowledge management (KM), and knowledge networks (KN). The document also clarifies the roles and responsibilities of key stakeholders, including government bodies, regulatory authorities, technical support organizations, operators and educational institutions, in developing, implementing and periodically assessing capacity building needs. It includes a comprehensive self-assessment questionnaire.