Outbreaks of staphylococcal skin infections among healthy adults are most unusual. The authors report an epidemic of skin infections due to Staphylococcus aureus that involved river rafting guides in Tennessee, South Carolina, and North Carolina in summer 1982. Infections occurred only among employees of the rafting companies that provided communal, on-site housing; carriage rates of S. aureus were as high as 89% at those companies. A case-control study found that having had an infected roommate was significantly associated with infection, as was working at the livery with the most crowded housing. This outbreak appeared to be due to two factors: frequent minor skin wounds acquired while rafting, and prolonged close contact among the persons with wounds. It is likely that crowding and exposure to infected wounds led to elevated S. aureus carriage rates, which in turn increased the probability that wounds would become infected. Repeated immersion in water likely enhanced the development of infections.