This is a research design paper. This research examines the extent that public evaluations toward American political institutions are a function of similar or divergent factors. Ramirez (2013b) shows that institutional approval of Congress decreases when it fails to meets its function of passing policies (Ramirez 2009). Rather than evaluating political actors based on a single criteria (i.e., the economy), citizen should perceive different roles or functions for each institution and make evaluations according to outcomes related to those functions. The specific attributes that citizens use in making evaluations should derive from the structure of government -- specifically the separation of powers -- which creates both shared and independent responsibilities for American political institutions. It is this characteristic of the U.S. political system that leads to both shared and idiosyncratic factors that drive public support. The theory is tested using an array of experimental, time-series, and cross-sectional models.