Black students' experiences in math and science courses in urban high schools were investigated. A critical race theoretical framing of qualitative data revealed teacher characteristics that encouraged and discouraged students. Teacher characteristics that encouraged students' interests included (1) shared racial/cultural background with students, (2) passion for students and subject matter, and (3) a caring and understanding approach to student engagement. Characteristics that discouraged student engagement included (1) lack of racial representation, (2) differential treatment of students based on race, (3) condescension and assumed incompetence, and (4) technology as a replacement for instruction. We offer recommendations to improve Black students' experience and increase interest in pursuing future STEM careers.