Contractor personnel provide essential services to nuclear power plants (NPPs). They have required levels of competency and must interface effectively with nuclear power plant personnel when performing their assigned duties. It is in this context that this publication offers a framework for assuring the competence of such contractor personnel. This publication reflects the latest practices relevant to the involvement of contractors at NPPs, and details the means currently used to assure their competence. It seeks to provide an understanding of the definition and use of contractors and how they are engaged through the contracting process. The publication will be a useful resource for managers and team leaders of nuclear facilities who are responsible for the competence of NPP personnel including contractors; training staff who are involved in the contracting process; subject matter experts who are involved in the contract specification, and project managers and other staff who may have responsibility for contractor personnel on site.