Instructors often encounter challenges in the implementation of evidence-based teaching practices in large-enrollment STEM courses. A novel Instructional-Teams Model (I-TM) seeks to address some of these challenges with the support of student assistants in specialized roles. I-TM roles focus on supporting course and classroom management (instructional managers), formative assessment (learning researchers), and student engagement (learning assistants, who are already a common feature of many large-enrollment STEM courses). We analyzed benefits and challenges in teaching with this model as expressed by participating instructors. Our results support the utility of the I-TM for implementing evidence-based, active-learning instruction in large-enrollment STEM courses.