COSPONSORSHIP IN THE US CONGRESS

Over half of all bills introduced in the U.S. Congress are cosponsored , and, while many observers assume that cosponsorship is crucial to th e legislative process, few have analyzed what it means. We view cospon sorship as a signal about the content of legislation and ask whether i t is a meaningful signal for members. Specifically we focus on whether cosponsorship influences a bill's passage. Three types of signals are considered: bandwagon, ideological, and expertise. Using data drawn f rom the 99th Congress, we analyze 8,002 House and Senate bills. Our fi ndings show that cosponsorship is common. However, they also show that it is an overrated cue. At best it provides a signal concerning exper tise at the outset of the legislative process, but generates a very we ak signal thereafter. In short, cosponsorship has become a routine and rarely effective aspect of the legislative landscape.