ABSTRACT Scholars in Second Language Acquisition (SLA) have long called for a reconceptualization of the field, in which sociocultural understandings of the nature of language, language use, and language acquisition are placed on an equal footing with cognitive understandings. This study, through an in-depth exploration of the beliefs, perceptions and practices of high-school level English as a Second Language (ESL) teachers and an analysis of the programs that prepared them, reveals a number of reasons why such a reconceptualized understanding of language is crucial to the success of teacher preparation programs in preparing candidates to work effectively with adolescent English Learners (ELs). Data for this qualitative collective case study was gathered both from secondary-level ESL teachers in non-gateway school districts in a Midwestern state and from teacher educators at those institutions of higher education attended by participating teachers. The data is comprised of interviews with both groups of participants as well as observations of teachers' work. Analysis suggests that the skills and knowledge upon which secondary-level ESL teachers in non-gateway districts draw in working with ELs may be restricted by their experiences with teacher preparation programs that embrace a narrow conception not only of the nature of language, language use, and language acquisition but also of teachers' work. Recommendations are offered for enhancing the effectiveness of preparation programs in readying ESL teachers for their work. While this study will be of interest to all teacher educators, it holds particular relevance for those who prepare secondary-level teachers for their work with ELs in non-gateway districts. In thus focusing on secondary education in non-gateway districts, the study addresses a gap in the literature on ESL teacher preparation, which has typically focused on the needs of elementary-level ELs and ESL teachers in traditional urban gateway areas.