Members of Congress take more than 2,000 trips sponsored by private organizations and interest groups every congress. Using a new data set of gift travel from 2007 to 2019 and interviews with former members of Congress, current and former congressional staffers, and staffers from interest groups that fund trips, we attempt to answer two core questions about this increasingly frequent behavior. Why do members take privately sponsored trips and what types of groups are driving this behavior? We argue that members of Congress take trips because they believe it makes them more effective legislators by exposing them to real-world consequences of their policy decisions and forcing them to build relationships with their fellow members. Trip sponsors, alternatively, seek to persuade and build relationships with members of Congress that ultimately shape their legislative coalitions. We find that trip-taking is associated with greater legislative effectiveness, in particular for Democrats, and that the provision of policy-specific information is a valuable benefit from taking these trips.