This study examined the teaching practices of Maria, a special educator who worked with students who had multiple disabilities, were nonverbal, and used augmentative and alternative communication (AAC). It highlighted the complex, interdependent, and dynamic nature of teacher knowledge, beliefs, and practices and evaluated what Maria knew and believed that led her to teach as she did. Data were collected via classroom observations, semi-structured interviews with Maria and members of her classroom team, and analysis of pertinent documents. Results indicated that Maria's beliefs about her students, her role and responsibilities as their teacher, and the nature of knowledge interacted to define her teaching practices. Maria's beliefs about students were strongly interventionist. The interventionist nature of her beliefs provided her with in-depth knowledge of her students characteristics, needs, and achievements. Her beliefs were broadly applicable to learners, irrespective of the nature of their differences. Ultimately, the interventionist nature of her teaching revealed her students competencies demonstrating that, despite their unique characteristics and significant barriers to communicating and learning, students who used AAC benefited from teaching practices that effectively supported student achievement. (Contains 39 references.) (SM)