Do assimilationist restrictions on a minority language lead to greater national unity or a more rebellious minority population? Under what conditions might short-term backlash to language assimilation evolve into greater national unity in the long term? While much of the literature on ethnic politics implicitly treats language simply as an identifying feature of ethnic groups, this dissertation contends that salient language identities and grievances can serve as a source of meaningful division. I examine when and why the costs of pursuing linguistic homogeneity exceed its practical benefits. Just as minority individuals must conduct a cost-benefit analysis to determine whether they should acquire or have their children acquire the dominant language of a host state, so too must governments consider the likelihood that an assimilation program will succeed or fail. I highlight an interaction between three key mechanisms that lead to a distortion of political leaders' cost-benefit analysis when deciding on the nature of their desired language assimilation program. This distortion leads host states governed by the dominant language group to systematically overestimate the willingness of minority individuals to assimilate voluntarily and underestimate the likely level of subsequent backlash to severe language restrictions. From this theoretical framework, I argue that more severe language restrictions increase minority backlash, and that the intensity of this backlash is influenced by the presence of exclusionary political and economic policies targeting the minority group. To this end, I conduct five comparative historical case studies on the language assimilation programs imposed on the South Tyroleans in Italy, Amazigh in Algeria, Azerbaijanis in Iran, Mayans in Mexico, and the Anglophones in Cameroon. The overall findings show that the use of more severe language restrictions and exclusionary political and economic policies are very likely to result in intense backlash responses. More often than not, this elevated backlash response will inflict considerable long-term damage to a state's national unity. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]