Civic participation in the United States is highly unequal, resulting in a "civic engagement gap" between socioeconomic, racial, and gender groups. Variation in civic participation and the civic engagement gap remain contested, primarily as a result of inconsistent definitions and measurement issues in previous work. Using consistent measures from the Monitoring the Future Study from 1976 to 2009, I analyze whether sociodemographic gaps in youth civic participation changed during a period of growing income inequality. I find that since the 1970s, electoral participation decreased, volunteering increased, and social movement activity remained constant. Participation varied by sociodemographic group, with highly educated Whites most active in all activities. Females volunteered more than males, but participated at the same rate in all other activities. The gap between male and female volunteering increased over the time period, as did the socioeconomic gap in volunteering. Racial gaps in participation, however, remained relatively stable from 1976 to 2009.