There are many reasons, moral and practical, why we need to diversify our mathematics departments — and more generally STEM departments and the workforce. But how do we go about it? A good starting point is to realize the various barriers to an inclusive environment. In this talk, a case study will be used to illuminate some of those roadblocks. This will help us think more critically about how those barriers arise, where they arise (teaching and learning, undergraduate life, graduate student admissions and training, faculty hiring and support, etc), why they may be difficult to spot, and what we can do to break them down. But it is not enough to address obstacles. A next step is to seek feedback, to listen — and to trust the perspectives and experiences of marginalized students and colleagues. Those voices need to be elevated and prioritized so we can begin to act in responsive, respectful, helpful ways; and break down more barriers.