This Measurement Good Practice Guide aims to provide introductory guidance on wear testing for coatings using the ball cratering or microabrasion wear test. Although the focus of the Guide is on abrasion testing, the use of ball cratering for unlubricated wear and friction testing is also covered.The guide also contains a discussion on the most effective approach to wear testing and considers the different aspects that should be taken into account when designing a programme of friction and wear testing.Specific guidance on how test conditions should be set and the procedures that should be used are given in Appendix A.