Tests are updated and revised periodically in order to remain current, valid and reliable in a competitive psychological testing industry. Despite the prevalence of test revisions, especially in recent years, a number of authors have commented on the lack of comprehensive guidelines for test revision. Whilst some guideline documents from test associations have mentioned test revision, these guidelines tend to be focussed on test user responsibility, with limited guidance for practitioners embarking on a test revision project. Test revision is expensive and time consuming, leaving little scope for experimentation or trial-and-error. Test revision deserves a comprehensive document that addresses aspects such as what the different types of revision are, when to embark on a revision, what process to follow and how test users should use revised tests. The current study developed a comprehensive and practical set of 23 guidelines across ten phases of a revision project to assist revision teams, test users and publishers. These guidelines were peer-reviewed and refined.