Multi-source feedback (MSF) has become the accepted mechanism of ensuring the appropriate professional behaviour of doctors. It is part of the mandatory assessment of doctors in training and is to be utilized as part of the revalidation of trained doctors. There is significant variation in the models of MSF currently used within the National Health Service and new models of MSF are being designed by various specialties. No single model has been recognized as the 'gold standard'. However, there is a large published literature concerning MSF, both in the context of health systems and, more extensively, within industry. This published literature is reviewed, drawing attention to aspects of MSF systems in which there is consensus on effective approaches as well as other aspects in which there is doubt about the optimum approach. In the light of the review 10 principles key in the development of effective MSF models have been produced.