Discipline-based education research has made great strides in understanding how to improve the teaching and learning of science, technology, engineering, and mathematics (STEM). However, there still has yet to be widespread adoption of reforms in university STEM departments. Our project seeks to understand how departments can implement sustainable, large-scale changes. We facilitate Departmental Action Teams (DATs), teams of faculty, students, and staff within a single STEM department working on some issue related to undergraduate education. During this talk, I will present an overview of the DAT model and the principles which guide our work. I will then present some empirical research discussing how to meaningfully incorporate student voice in departmental changes. Finally, I will discuss the multifaceted nature of complex change.