Questions regarding the concept of legitimacy are central to social and political science. Exploring how people justify legitimacy and why people grant legitimacy to leadership and collective decisions in groups, organizations, and nations is generally agreed to be essential to scholarship on legitimacy. One line of research finds contributing factors in bureaucratic effectiveness and efficiency that can provide substantive benefits to people. Another line of research expands legitimacy to procedural elements such as fairness of treatment or quality of communication (deliberation) in the decision making process. This dissertation intends to contribute to the research of legitimacy and hopes to further the understanding of communication's role in decision outcome legitimacy by incorporating two sets of contributing factors: Performance factors and communication factors. This will enable a side-by-side comparison of instrumentalist and communicative factors in predicting legitimation. In addition, the study will observe the quality of the communication environment as a contextual variable upon which the relationship between performance elements and decision outcome legitimacy depends. Specifically, how the communication environment moderates the strength of the relationship between output of public service in a certain domain and the perceived legitimacy of the decision made in the same domain will be observed. Drawing on the framework from Habermas's theory of communicative action and the public sphere, the literature on deliberative democracy, and organizational studies, the project intends to observe how the communication environment or speech conditions (in Habermasian terms) may affect the legitimacy of a decision outcome, and at the same time may influence the relationship between the perceived performance in a certain public service sector and the perceived legitimacy of a decision outcome in the same sector. Using a sample of 255 adult residents in Chengdu, the capital city of Sichuan province in southwest China, the study found that perceived government performance and perceived speech conditions were both positively related to perceived legitimacy of government decision; furthermore, perceived speech conditions moderated the relationship between the performance evaluation and legitimacy perception. These findings suggest some important insights into the role of communication in political legitimation and the evolving communication expectations in China. / Mass Media and Communication