The Dominant Role of Teachers’ Social Capital in Shaping School Well-Being: A Regression Analysis of Muhammadiyah Schools in Karanganyar

School well-being is a critical precondition for sustaining education quality in madrasah institutions shaped by Islamic values and Muhammadiyah's organizational culture. This study empirically examines the partial and simultaneous effects of principals' academic supervision and teachers' social capital on school well-being among 86 teachers at Muhammadiyah Islamic elementary schools (Madrasah Ibtidaiyah) in Matesih Subdistrict, Karanganyar Regency, and identifies which factor is more dominant. A quantitative correlational approach with an ex post facto design and total sampling technique was employed. Data were collected through validated and reliable Likert-scale questionnaires, then analyzed using multiple linear regression after classical assumption tests were satisfied. Both variables were partially significant, but when tested simultaneously, only teacher social capital remained significant (β = 0.739; p = 0.000), while academic supervision became non-significant (β = 0.104; p = 0.190). Together, both predictors explained 63.1% of the variance in school well-being (F = 73.560; p = 0.000). These findings confirm the dominance of teacher social capital, likely due to overlapping variance between predictors. Strengthening school well-being in madrasah settings therefore requires deliberate investment in trust, networks, and reciprocity among teachers, not merely formal supervision.