In this article, we develop the concept of nascent political ambition and offer the first empirical assessment of potential candidates' initial interest in seeking elective office. Our analysis is based on the Citizen Political Ambition Study—our national survey of nearly 3,800 individuals in the four professions that most frequently precede a career in politics. We find that a general sense of efficacy as a candidate, as well as a politicized upbringing, motivate well-situated potential candidates' inclinations to run for office. Alternatively, status as a member of a group historically excluded from politics depresses the likelihood of considering a candidacy. These findings shed light not only on the prospects for political representation and democratic legitimacy in the United States, but also the means by which to study candidate emergence and conceptualize political ambition.