This Good Practice guide aims to provide guidance on erosive wear testing. It contains a description of the four common erosion test systems (gas jet; centrifugal accelerator; wind tunnel; whirling arm), and a discussion on the important variables in erosion such as particle impact velocity, particle impact angle, particle size, shape and material, and ambient temperature. A short review of techniques for data analysis and interpretation is also included.It also contains a discussion on the most effective approach to wear testing and considers the different aspects that should be be taken into account when designing a programme of friction and wear testing.In Annex A, specific guidance is given on gas jet erosion, on how test conditions should be set and the procedures that should be used.