This publication provides practical advice for planners to prepare, conduct and evaluate nuclear material transport security exercises. Nuclear material transport security exercises are part of a comprehensive nuclear security regime. Exercises vary in scope and in scale, ranging from small drills, which focus on training, to large scale exercises, which aim at testing the overall command, control, coordination and communications arrangements. The purpose of exercises is not to `demonstrate’ the quality of the arrangements, but rather, to identify weaknesses and areas where improvements can be made. Hence, exercises are an integral part of a sustainable and continuous improvement programme for nuclear transport security. Exercises can also be a tool to assess and validate existing transport security arrangements prior to gaining regulatory approval for actual transport operations or transport campaigns. The material provided in this publication is intended as an example of a logical process for the preparation, undertaking and evaluation of exercises, which needs to be adapted to suit national systems, local circumstances and the specific aim of each exercise. It constitutes a starting point for organizations that have not previously organized or managed exercise programmes, as well as a reference for organizations that wish to validate or improve their existing exercise programmes.