The survey data presented here are on the national prevalences of major life-time perceived discrimination and day-to-day perceived discrimination; the associations between perceived discrimination and mental health; and the extent to which differential exposure and differential emotional reactivity to perceived discrimination account for the well-known associations between disadvantaged social status and mental health. Although more prevalent among people with disadvantaged social status, results show that perceived discrimination is common in the total population, with 33.5 percent of respondents in the total sample reporting exposure to major lifetime discrimination and 60.9 percent reporting exposure to day-to-day discrimination. The associations of perceived discrimination with mental health are comparable in magnitude to those of other more commonly studied stressors, and these associations do not vary consistently across subsamples defined on the basis of social status. Even though perceived discrimination explains only a small part of the observed associations between disadvantaged social status and mental health, given its high prevalence, wide distribution, and strong associations with mental health, perceived discrimination needs to be treated much more seriously than in the past in future studies of stress and mental health.