在近數十年來的美國社會，「語言多樣性」一直是個充滿爭議性的話題。自一九八○年代「唯用英語」運動興起以來，即在各州積極推動將「英語為官方語言」明訂為州法，與聯邦政府的雙語教育政策形成對立衝突。本文採用語言政策和規劃的理論觀點，從美國語言政策之歷史演進切入，深入探討此一語言政策衝突，並進一步分析導致該衝突形成之主要意識形態。結果顯示，造成衝突的癥結並非是語言多樣性本身，而是肇因於大量移民湧入後，對原有的社會政治及權力結構所可能引發之衝擊和改變而產生的效應。文末並對未來美國語言政策之規劃方向提出建言。

Linguistic diversity, a phenomenon that has existed in the United States since the beginning of its history as a nation, has become a highly contentious issue in recent decades. As a result of the continuous controversies over English-only/Official vs. bilingual education/bilingualism, language policy and planning have often come to the forefront of political debates in the United States. This paper critically examines U.S. language controversies within several dominant theoretical frameworks of language planning and policy. The examination indicates that under the tremendous impact of the dominant language-as-problem orientation, standard English, and English monolingualism, U.S. language policy is largely restrictive in nature, and heavily encumbered by politics and ideology. The real agendas underlying the language policy debates of the early 21st century are not about language per se; rather, they are more about immigration. Specifically, the source of language controversies lies in the more fundamental problems regarding social stratification and inter-ethnic competition, rather than the increased language diversity in the contemporary American society. This paper concludes with several proposed avenues to shape a more supportive and positive language policy in the U.S..