The effects of party and preferences on congressional roll-call voting

We assess the importance of parties in Congress by comparing roll-call voti ng behavior against the preferences of members of the House as expressed in surveys conducted during the 1996 and 1998 elections. The surveys were con ducted by Project Vote Smart. Our findings support two key conclusions. Fir sts both party and preferences mattered in predicting roll-call behavior in the 103d, 104th, and 105th Congresses. Second, the independent effects of party were present in only about 40% of roll calls. The incidence of party effects was highest on close votes, procedural votes, and key "party" issue s. It was lowest on matters of conscience, such as abortion, and "off-the-f irst-dimension" issues, such as affirmative action and gun control.