This paper deals with the question of parliamentary control of the executives of 22 Western democracies. Based on principal-agent theory, it aims to analyze the instruments of control and the control capacity of parliamentary principals vis-à-vis their governmental agents. In a first step, parliamentary resources are discussed as an important means to bridge the information gap between parliament and the executive. In doing so, the paper focuses on parliamentary committees, their institutional structure, their membership, and their formal powers without neglecting further parliamentary information resources like question times, accounting offices, or scientific and library services. Based on this discussion, data is presented to characterize structural, formal, and personal parliamentary information resources. This presentation is summarized by an empirical mapping of the character and properties of parliamentary control structures in Western democracies. The data is then used to answer questions about systematic relationships between parliamentary control resources and the political strength of the executive. The most important result of this analysis is that there is no systematic relationship between political strength of executives and parliamentary control resources. Even politically strong governments are not able to systematically curtail the control resources of their parliaments.