The much venerated Senate of the mid-twentieth century is now a distant memory. Today senators routinely electioneer on the Senate floor, play games with the legislative process, and question each other’s motives. Sean M. Theriault documents how one group of senators has been at the forefront of the transformation—the “Gingrich Senators,” which he defines as those Republicans who previously served in the House after New Gingrich was first elected. He shows how the Gingrich Senators are more conservative and more likely to engage in partisan warfare than the other Republicans.