Affective contagion is a process of transferring of mood or emotions between individuals. The process often occurs among people who work together and leads to the activation of collective emotions and moods. In particular, it refers to the work teams whose members often cooperate, have positive relations with each other, and are interdependent. Collective affective states can also be shaped by a manager whose feelings spread over other members of the work team. The author discusses the stages of affective contagion and reviews the research on affective contagion at work. She also characterizes the consequences of the spread of collective states between workers for their functioning at work. Individual differences in susceptibility to affective contagion as well as in tendency to affect others with one's feelings are also discussed. Med Pr 2010;61(2):223-232