For promise keeping to occur at high rates, candidates must have the incentive to make sincere appeals in their campaigns and winning legislators must have the motivation and the opportunity to follow through on these appeals once in office. For it to be meaningful, the actions legislators take on their campaign promises must not be solely symbolic. This chapter addresses both of these issues. I first establish in more detail legislators' reasons for engaging in promise keeping and discuss why the content of their governing agendas serves as a useful target for measuring this responsiveness. I then develop hypotheses about variation in this behavior at the individual and aggregate levels. I anticipate that promise keeping will be widespread, but that levels will vary in a predictable fashion across types of appeals, across legislators, across activities, across chambers, and across time.

As is conventional in work on legislative behavior, I begin with the assumption that reelection is legislators' most proximate goal (Mayhew 1974). As such, I expect that legislators will not knowingly endanger their electoral prospects and will devote time and effort to actions that promote them. To the extent that promise keeping helps them to accomplish this goal, we should observe them engaging in it at high rates. At the same time, though, I also assume that reelection is not legislators' sole goal, that there is not a single route to achieving it, that it is interconnected with legislators' other goals, and that there is at least some path dependency at work.