Women and people of color are severely underrepresented in many STEM departments, especially in physical sciences and engineering. Professional societies and universities have issued reports full of recommendations. Which ones have worked? This talk will identify departments that are most successful in diversifying bachelor’s and doctoral degrees in STEM. Using data on student and faculty demographics, departmental practices, and interviews, I will present evidence as to how successful departments in physics, engineering, and other STEM departments at MIT and across the nation succeed in creating environments where all students can thrive.