Using self-determination theory, we sought to explain how teachers learn autonomy-supportive teaching. We randomly assigned 28 teachers (35.3 years-old, grades 7-9) and their 1566 students (13.4 years-old, 50.8% female) to participate or not in an autonomy-supportive teaching workshop. Teacher participation in the workshop increased autonomy-supportive teaching. Results from a multilevel structural equation modeling analysis showed that teachers in the experimental, compared to the control, condition first learned perspective taking skill, then learned the three teaching practices of interest support, value support, and lesser teacher control, which then explained their students' year-end gains in need satisfaction and declines in need frustration.