Using data from North Carolina and Florida, this paper examines whether teachers in high-poverty schools are as effective as teachers in schools with more advantaged students. Bottom teachers in high-poverty schools are less effective than bottom teachers in lower-poverty schools. The best teachers, by comparison, are equally effective across school poverty settings. The gap in teacher quality appears to arise from the lower payoff to teacher qualifications in high-poverty schools. In particular, the experience-productivity relationship is weaker in high-poverty schools and is not related to teacher mobility patterns. Recruiting teachers with good credentials into high-poverty schools may be insufficient to narrow the teacher quality gap. Policies that promote the long-term productivity of teachers in challenging high-poverty schools appear key.