在傳播領域，多元化一直是媒介追求的目標，但是何謂多元化卻是一個尚未被精確界定的名詞，多元化雖源於政治上的多元主義，但隨著民主政治的發展，媒介多元化的概念亦隨之成長。多元化的意涵除了指涉政治多元所含蓋的「競爭」、「參與」、「分權」及「制衡」等概念外，更包括媒體表現的多元，多元主義在大眾傳播的實踐已被視為抗拒媒體單一化、提供更多選擇、反映社會差異、落實言論自由與保障少數族群傳播權益的重要理念。國內目前有關多元化的論述尚未成熟，也未將多元化的概念具體落實於傳播政策的設計，實證研究更為缺乏。本論文藉此檢視有關多元化概念的相關理論，追溯多元化概念的淵源背景，分析媒介多元化的政策理念，並釐清媒介多元化概念之面向與意涵，以作為建立客觀評量媒介多元化的指標依據。根據此一指標架構，進行電視節目內容多元化的實證研究，分析台灣電視媒體在多頻道環境下的節目多樣性，以及新電台加入對節目多樣性所造成的變化。 / The value of media diversity has always been pursued as an end for mass media, but questions about what are the concepts of diversity are not specifically defined. Although diversity has its primary reference to political plural concept of separation of powers, the appeal of diversity for mass media in modern society has been extended as a critical response to centralized control and conformity by providing the social difference and minority access, maximizing consumer choice and encouraging alternative voices and expression. In Taiwan, few of the questions for diversity research are systematically investigated and the diversity principle hasn''t been fully implemented in media policy. This thesis reviews the related literature of media diversity and develops a framework of analysis to guide the empirical research. The purpose of this study is to investigate the TV program diversity by collecting programming data of nine networks in Taiwan. The systematic quantized data and possible explanations for this result were discussed in the thesis.