This study examines mainstream teachers' knowledge, beliefs and attitudes, and classroom practices in relation to English language learners. The study was guided by four questions: (1) What professional knowledge do mainstream teachers have about teaching English language learners, and where and how did they learn what they know? (2) What beliefs and attitudes do teachers have about teaching ELLs? (3) How do teachers' professional knowledge, beliefs, and attitudes influence their teaching practice? (4) What are the ways teachers' environment shapes their practices in terms of English learners? In the frame of three case studies with three mainstream teachers in grades 1 and 2, the several findings were discovered: (1) In terms of the teachers' knowledge, none of the teachers were sufficiently prepared to work with ELLs. Although their practices included good pedagogy, it did not appear to be enough in supporting the academic needs of ELLs. (2) While all of the teachers indicated positive attitudes toward ELLs, the lack of knowledge in how best to work with them often had strong negative consequences, especially in the participation of ELLs in the classroom learning. (3) In regard to the actual practice of the teachers, it was found that each of the six ELLs' academic growth was compromised in some ways; however, most of the negative consequences of the teachers' inability to work with them were not readily apparent in the classrooms. (4) From the three cases, it also appeared that the community context in terms of the relationship between immigrants and natives substantially filtered into the decision-making process of the schools. While in each case, there was an attempt to address the needs of ELLs at least to some degree, none of the schools problematize the education of their non-native English speaking population. The findings of this study support that teacher education programs must reform themselves in order to address the cultural and linguistic realities of today's classrooms, and they must do so in a comprehensive way. Teachers need to understand the multiple factors affecting the education of ELLs, including the social, cultural, and political contexts in which schools are embedded. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]