Although there is a large literature on children's reasoning about contagion, there has been no empirical research on children's avoidance of contagious individuals. This study is the first to investigate whether children avoid sick individuals. Participants (4- to 7-year-old children) were invited to play with two confederates-one of whom was "sick." Afterward, their knowledge of contagion was assessed. Overall, children avoided proximity to and contact with the sick confederate and her toys, but only 6- and 7-year-olds performed above chance. The best predictor of avoidance behavior was not age but rather children's ability to make predictions about illness outcomes. This provides the first evidence of behavioral avoidance of contagious illness in childhood and suggests that causal knowledge underlies avoidance behavior.