How do teaching styles and school environments - across Laboratory School Bielefeld, Montessori, Waldorf, Jena Plan, and public schools - shape students' well-being and intrinsic motivation in mathematics? Drawing on Self-Determination Theory (Deci & Ryan) and Structuration Theory (Giddens), this multilevel mediation study of 1,431 German students reveals that positive, need-supportive teaching fosters well-being as a key pathway to intrinsic motivation. Teacher effects, analyzed at the course level, outweighed school-type differences. Intrinsic motivation was highest in traditional school environments, while well-being peaked in non-traditional ones, highlighting the central role of teachers in shaping students' emotional and motivational experiences.