This dissertation examines the effect of partisanship on stages of the appropriations process in American government. In the American separation of powers system, three policymaking institutions with differing constituents and decision-making structures bargain to determine budget outcomes. The central theory posits that institutional actors are strategic in constructing appropriations requests indicating that they base their decisions on both their institutional preferences, but also on the preferences of other veto-wielding actors. An accommodating bargaining strategy, structured by partisan control of each institution, results in appropriations requests that account for the policy preferences of other veto wielding institutions. Two unique data sets at the national and state-level are analyzed to gain a broader understanding of the effect of partisanship and strategic bargaining on the appropriations process. Pooled time-series regression analysis is utilized to examine the relationship between partisanship and appropriations requests and outcomes, controlling for a series of institutional and economic characteristics. The study results indicate that partisan institutional control structures the bargaining process, appropriations requests, and final budget outcomes. This study advances our understanding of the role of partisanship in shaping the appropriations process in American government.