Chapters 3 through 5 are based on two datasets of state legislators. State legislators are particularly important for the “how” of polarization because they comprise the pool of would-be quality congressional candidates. State legislative office is the main pipeline to congressional office, and former state legislators comprise fifty percent of sitting members of Congress. Chapter 3 draws on survey data of legislators that were collected for the Candidate Emergence Study to examine the perceptions of state legislators (Maestas et al. 2006). The analyses demonstrate that moderates are less likely to be attracted to a congressional career, less likely to think they can win, and less likely to value a seat in the U.S. House than those at the extremes. These differences are largely restricted to the Republican side, but the results also reflect distinctions between the two parties and the time period in which the survey was conducted.