Active learning classrooms (ALCs) support teaching approaches that foster greater interaction and student engagement. However, a common challenge for instructors who teach in ALCs is to provide adequate assistance to students while implementing collaborative activities. This study examined the impact of teaching assistants in a large ALC. The results showed that incorporating teaching assistants increases students' access to expert advice during small group activities; further, students view the teaching assistants as supportive of their success in the classroom. Therefore, along with classroom design and pedagogical approach, availability of teaching assistants for instructors teaching in large ALCs must be considered.