Knowing how campaign contributors influence policymaking is important for understanding political power, but the existing literature—much of it outside sociology—has mixed findings. Using data on Political Action Committee (PAC) contributors and roll call voting in eight U.S. Houses, 1991–2006, I approach the issue using a novel, sociological approach that focuses on social ties between lawmakers and mutually shared contributors. The findings show consistent, statistically significant contributor influence via these ties in seven of the eight Houses. I discuss the implications of these findings for contributor-lawmaker reciprocal exchange, the social embeddedness of policymaking, and political power.