Organizational innovation in Senate parties is not continuous. Innovation is time-consuming and causes rifts among senators and so has been most likely to occur when the short-term payoff, in terms of the goals of majority party control and winning legislative battles, is substantial. The payoff is likely to be greatest when party strength is close to parity. Our central theme has been that modern party leaders advance their parties’ legislative and electoral goals by managing their party organization, coordinating party activities on the floor, serving as intermediaries with the president, building coalitions, and serving as party spokespersons. We have emphasized throughout this book that legislative and electoral goals are usually pursued in tandem. The process of organizational invention is sporadic. But it is also one of the nearly monotonic increases in the organizational capability of the two parties since the creation of party caucuses in 1841.