This publication is a revision of IAEA TECDOC No. 1263 and offers practical guidance for establishing, implementing and improving in-service inspection programmes based on non-destructive testing methods for research reactors. The publication addresses all aspects of programme development and execution, including its review and continuous improvement. It adopts a methodological approach and incorporates practical examples from operating research reactors to support programme implementation. This guidance is intended for research reactor operating organizations, designers, and support organizations.