Over past decades, there has been a paradigm shift in WL instruction, moving away from traditional, grammar-based programs and toward instruction that promotes student proficiency in the target language. Despite this growing attention to proficiency-based instruction, few studies have investigated the relationship between proficiency-based programs and student outcomes. Thus, in the present study, the researchers used a mixed methods approach, involving the collection and analysis of assessment and interview data, to investigate the relationship between approach to language teaching and oral proficiency outcomes of high school students enrolled in Level III Spanish, French, and Chinese classrooms. More specifically, the study explored how a proficiency-based approach enhanced the oral proficiency outcomes of students in comparison to a traditional grammar-based approach, and how teachers and students perceived the different learning environments. Quantitative data revealed varied oral proficiency development, based on language of study, and that students in the proficiency-based program had greater oral proficiency than their counterparts who completed the traditional grammar-based program. Qualitative data suggested that when compared with the grammar-based program, instruction in the proficiency-based program was perceived by students to be more relevant and led to more motivated and confident students. Recommendations are provided based upon these critical findings.