Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) has emerged as a major cause of skin and soft-tissue infections world-wide. One of the most striking features of this emergence has been the impact on indigenous communities, including Australian Aboriginals, Alaskan Inuits, Americans Indians and Pacific Islanders. However, these are not the only groups at risk, with outbreaks of CAMRSA reported in day care centre attendees, sporting teams, prisoners, military personnel, drug addicts and men who have sex with men. What risk factors are common to these groups which, on the surface, look quite disparate, and, in some cases, are geographically isolated? The most likely are close contact and poor hygiene. If antibiotic selective pressure is then applied, a potentially explosive situation may develop that explains the rapid spread of CAMRSA in these defined populations and now to the general community. But what was the mechanism for the emergence of CAMRSA initially? Clones of MRSA containing SCCmecIV appear to have arisen simultaneously in various parts of the world in the early 1980s. Why did this occur? Once again antibiotic selective pressure is likely to be important, and cephalosporins are likely to be the culprits. Whether CAMRSA will replace methicillin-susceptible Staph. aureus in the community, as was suggested initially, or simply be an additional burden, remains to be seen. Either way, preventing both the emergence of new strains of CAMRSA and the spread of those already in circulation will provide a significant challenge to infectious diseases, infection control and public health practitioners.