The contribution of human performance to the occurrence of significant events and consequently to overall performance improvement in the nuclear field has been well documented. Nuclear industry experience shows that within nuclear power plants, 80% of significant events can be attributed to human error. Monitoring and continually improving human performance has now become one of the key challenges in the management of human resources for a nuclear facility. This publication provides practical guidance in this area and will assist Member States to review and improve the systems and process for improving human performance as a major contribution to sustaining and improving the performance of nuclear facilities.