Adolescent learners must deal with the challenges of physical, social, emotional, and intellectual changes as well as increasingly demanding content. In turn, these challenges affect practicing middle school teachers, who also face complex issues with diverse student populations. The purpose of this qualitative case study was to determine how four middle school content teachers joined their understanding of multiple intelligences theory with their application of multiple intelligences-based activities in their respective content area classrooms. The research questions focused on an examination of theory understanding, lesson implementation, and teacher reflection on the effectiveness of multiple intelligences-based activities. Each of the four major content areas was represented (i.e., social studies, math, science, language arts). Data were gathered through semi-structured interviews, classroom observations, reflective interviews, and example documents that had been used in classrooms. Transcribed data were analyzed through multiple readings that guided the development of categories and codes through typological analysis related to the research questions. Findings were presented by themes and individual case studies. Key findings indicated that teachers would benefit from additional training in multiple intelligences theory and that time and collaboration with colleagues would aid the development of application lessons. Findings also expressed a need for more deliberate teacher reflection on lesson effectiveness. This study indicates that positive social change can occur when middle school teachers, with a strong understanding of multiple intelligences theory and classroom application, use activities and techniques to create an instructional design that meets the needs of their diverse student populations.