The thesis examines the role of partisanship in two sessions of the Oregon Legislature. Both the Oregon Senate and the Oregon House of Representatives were examined for the 56th (1971) and the 57th (1973) session. Indicies of partisanship, or party cohesion were developed for both parties in both houses during both sessions. Each legislator was also assigned an index of partisanship. The indicies of partisanship for the parties were the average percentage of the members of the two parties voting together on those issues which underwent "party votes." A party vote was defined as any vote on which the majority of one party was opposed by at . least the majority of the other party. The individual index of partisanship for each legislator was that percentage of time the legislator was on the same side as the majority of his or her party during party votes. These two indices, of party partisanship and individual partisanship allowed comparison of the parties themselves and various subgroups within the parties such as urban legislators, legislators under thirty years of age and women legislators. All calculation was done by means of a special program on an IBM 1130 computer.