<p>Theories of ambition have taught us that higher offices are valuable commodities to certain politicians, and under the right circumstances, the benefits of running for an office outweigh the associated risks. Yet some ambitious politicians emerge as candidates while others do not. In this dissertation, I present a Theory of Strategic Candidacy Decisions to explain how primary elections unfold. With new comprehensive data on the timing of candidacy decisions, I test several hypotheses regarding the determinants of electoral and fundraising success, the timing of strategic candidacy decisions, the interactions of prospective officeholders, and the impact of strategic retirements on primary races for the United States Senate. Using both qualitative and quantitative tools, including event history techniques to capture the complex dynamics of primaries, I find that potential candidates interact with one another and the unique political context within each race and emerge from the pool of potential candidates in systematic ways. In the end, the strategic behavior of ambitious politicians has implications for the slate of candidates available to the electorate and ultimately, on the quality of representation between legislators and constituents.</p> / Dissertation