The scientific literature relevant to the arguments for and against the English-only movement is reviewed to determine whether the Resolution Against English Only before the Board of Directors and the Council of Representatives of the American Psychological Association (APA) was supportable. Some of the misconceptions advanced by English-only advocates that affect the sociopsychological, educational, testing, and health-service delivery arenas are examined. It is argued that there is no support for English-only initiatives, and that the English-only movement can have negative consequences on psychosocial development, intergroup relations, academic achievement, and psychometric and health-service delivery systems for many American citizens and residents who are not proficient in English. The public interest is best served by affirming a position in opposition to English-only. English-only is socially divisive and poses a threat to the human welfare that psychologists espouse in the APA Ethical Principles of Psychologists. (PsycINFO Database Record (c) 2012 APA, all rights reserved)