The search for party influence in the U.S. Congress has focused on flo
or voting patterns. By shifting the focus of attention to the committe
e setting, this paper shows that previous measures of party influence
have generally underestimated the strength of parties in Congress and
have invariably presented a simplified version of their activity. Meas
ures of party conflict, unity, and success in four House committees sh
ow that, in the differentiated committee system, parties structure vot
ing differently across decision-making environments and are stronger t
han on the floor. In the legislative environment of the 1980s, voting
patterns in all committees and on the floor converged toward partisans
hip, even as electoral and organizational indicators of party remained
relatively weak.