Any attempt to understand the legislative process, or to reckon how well it fulfills its purported functions, calls for a careful consideration of the relationships among congressmen. The beginning weeks of the first session of every congress are dominated by the internal politics of one phase of those relationships, the assignment of members to committees. Since congressmen devote most of their energies—constituents' errands apart—to the committees on which they serve, the political stakes in securing a suitable assignment are high. Competition for the more coveted posts is intense in both houses; compromises and adjustments are necessary. Members contest with each other over particularly desirable assignments; less frequently, one member challenges the entire body, as when Senator Wayne Morse fought for his committee assignments in 1953. The processes and patterns of committee assignments have been only generally discussed by political scientists and journalists. Perhaps the reason for this is too ready an acceptance of the supposition that these assignments are made primarily on the basis of seniority. Continuous service, it is true, insures a member of his place on a committee once he is assigned, but seniority may have very little to do with transfers to other committees, and it has virtually nothing to do with the assignment of freshman members. On what basis, then, are assignments made? Surely, not on the basis of simple random selection. A recent student sees the committee assignment process as analogous to working out a “giant jig saw puzzle” in which the committees-on-committees observe certain limitations.