This article sheds light on governance mechanisms at work when decentralised implementation of national educational and welfare policies encounters a heterogeneous sector of private service provider organisations. It illuminates how isomorphic pressure plays out at the interface between local governance and private providers' organisational strategies for quality development in early childhood education and care (ECEC). Key informant interviews are employed to investigate the function of local non-mandatory quality and competence-developing networks (QCDNs) as a locus for these interactions. Findings indicate that QCDNs contribute to shaping private ECEC providers' quality development efforts, and that coercive, normative, and mimetic isomorphic pressures become intertwined in this process. Most private provider organisations choose to participate in these non-mandatory networks. However, ECEC corporations and small private providers assign different meanings to their participation, and the networks thus appear to spur different organisational strategies. While small private providers harmoniously align their ECEC quality development strategies with institutionalised municipal practice, the provider corporations, while in formal compliance, exploit the resulting inter-municipal variation as one argument among many for more stringent national governmental standardisation. We demonstrate how isomorphic pressure may create and enable an impetus for endogenous and gradual institutional change agency.