women and men who work in the professions from which most candidates for elective office emergereveal a striking gender gap in political ambition (Lawless and Fox 2012;. Women are less likely than similarly situated men to consider running for office; less likely to run for office; less like to believe they are qualified to seek office; less likely to receive encouragement to run for office; and more likely to perceive a competitive, biased electoral environment (see also Fulton et al. 2006).Although the existing work on candidate emergence identifies and explicates the contours of the gender gap in political ambition among well-established potential candidates, virtually no political science research examines its origins (but see Elder 2004). We are very limited in the conclusions we can draw about the roots of the gap or the manner in which early life experiences shape it. This omission in the literature is critical because a general interest in, or openness toward, running for office early in life can set the stage for a political candidacy decades later. Young people's career goals, after all, tend to be excellent predictors of the occupations they ultimately attain (Ashby and Schoon 2010;Mello 2008;Trice and McClellan 1993). Many gendered attitudes about running for office, then, may result from deeply embedded socialized norms that are conveyed long before women and men find themselves in the candidate eligibility pool. Yet we simply do not know when young women and men's political ambition diverges, the extent to which it does so, or the factors that contribute to it. If the seeds of political ambition are planted at an early age, then gaining a complete understanding of the gender gap in ambition and prospects for women's representation demands that we pinpoint and explicate its origins.This article provides the first investigation to do just that. Based on survey responses from a national random sample of nearly 4,000 high school (ages 13 to 17) and college (ages 18 to 25) students, we uncover a substantial gender gap in political ambition. This is striking evidence that the gap is, in fact, present well before women and men enter the professions from which most candidates emerge. We then employ 499 Downloaded from https://www.cambridge.org/core.