Teachers in high-poverty schools often feel stressed and fatigued. We might expect that if we ask these teachers to take on even more work by meeting regularly in collaborative improvement teams, they will respond with skepticism, even resentment. But in a study of 83 teachers in six outstanding high-poverty schools, these researchers found the opposite. Teachers consistently reported that their teams reduced stress and gave them the support they needed to persevere. This article describes how teams operated in the five schools that made them the central component of school improvement. It also discusses the conditions that made teams effective in these schools, such as sacrosanct time in the schedule for team meetings; the school principal's active engagement with teams; facilitation of teams by teacher leaders; and the integration of other supports for teacher growth into the fabric of the school.