This publication seeks to provide a better understanding of the interface between safety and security at nuclear power plants and to discuss the means to achieve both objectives in an optimal fashion. It provides information in a background chapter on the existing relevant documentation, discusses the expectations for administrative arrangements at different levels, surveys certain common principles, and suggests general solutions that can help ensure an integrated approach. Conclusions are drawn and high level recommendations are proposed with the goal of maximizing the protection of the public, property, society and the environment through an improved and strengthened interface between safety and security.