How do ultra‐religious schools respond to state regulations that conflict with deep‐rooted cultural norms? This study investigates this question in the context of Haredi boys schools' decisions regarding Israel's core‐curriculum regulations. It draws on a first‐of‐its‐kind dataset of interviews and school data collected from a representative sample of 82 principals and teachers in schools serving 18,000 students and six government inspectors overseeing dozens of schools. We identify isomorphic structures of compliance and noncompliance and analyze the law's role among the competing sources of schools' decisions. These sources include rabbis, nongovernmental network supervisors, private consultants, models set by other schools, resource constraints, parents, and personal opinions. The findings reveal a tension between the law's overarching role in setting the baseline for schools' decisions and its under‐enforcement. We conceptualize this tension as a manifestation of coupled institutional maintenance, whereby ultra‐religious schools and government inspectors collaborate to maintain schools' noncompliance and autonomy.