Despite apparently consistent statements in four decades, the U.S. "one China" policy concerning Taiwan remains somewhat ambiguous and subject to different interpretations. Apart from questions about what the "one China" policy entails, issues have arisen about whether U.S. Presidents have stated clear positions and have changed or should change policy, affecting U.S. interests in security and democracy. In Part I, this CRS Report, updated as warranted, discusses the "one China" policy since the United States began in 1971 to reach presidential understandings with the People's Republic of China (PRC) government in Beijing. Part II records the evolution of policy as affected by legislation and key statements by Washington, Beijing, and Taipei. Taiwan formally calls itself the Republic of China (ROC), celebrating in 2011 the 100th anniversary of its founding. Policy covers three major issue areas: sovereignty over Taiwan; PRC use of force or coercion against Taiwan; and cross-strait dialogue. The United States recognized the ROC until the end of 1978 and has maintained an official, non-diplomatic relationship with Taiwan after recognition of the PRC in 1979. The United States did not explicitly state the sovereign status of Taiwan in the U.S.-PRC Joint Communiques of 1972, 1979, and 1982. The United States "acknowledged" the "one China" position of both sides of the Taiwan Strait.