Executive Summary Gauging the influence of organized interests in the American legislative process is undeniably a difficult undertaking. Interest groups and their lobbyists have little incentive to publicly reveal their goals and the extent of their efforts in pursuing those goals. Nationally, and in most states, lobbyists and interest groups are only required to publicly report their lobbying expenditures and the general policy areas in which they are interested in. Thus, it is extremely difficult to assess whether groups are successful in advocating for or against a particular bill. However, a few states have recently begun to require lobbyists and organized interests engaged in lobbying to report each specific bill they have lobbied and, in Wisconsin, whether they support or oppose the bill. These enhanced reporting requirements allow for a more systematic assessment of interest group influence in the legislative process. This study exploits this new data to address the question of lobbying efficacy by examining the outcomes of a random sample of bills introduced in the Wisconsin state legislature during the 2007-2008 session. By looking systematically at the extent to which lobbying and advocacy efforts affect the outcomes of introduced legislation, the analyses are able to show that these efforts, contrary to some of the recent research, have significant effects. Although contextual factors remain important, this study shows that advocacy efforts are influential in their own right. In addition, the analyses of this unique data reveal that several types of interest group activities (for example, campaign contributions) vary in their degree of influence at different points in the legislative process.