Codes of conduct organizations, like Organic farming or EurepGap, rapidly increase their impact on agribusiness. Yet, our understanding of these new institutional arrangements is limited. In particular, the question how criteria are developed and implemented by these codes of conduct organizations (CCOs) is of interest in order to understand how these organizations can contribute to animal welfare. A multiple case study was conducted, analyzing and comparing four cases that incorporate animal welfare issues: Freedom Food, Organic, EurepGAP and 'Scharrel'-eggs. The theory-building case studies eventuate in propositions on the criteria setting process in CCOs. In effect, setting norms comes down to weighing animal welfare (and possibly other ethical values) against market opportunities. The broader the sustainability goals of the CCO are and the more international the scope is, the more subcultures are present, making the process complex. When a CCO is based on positive values (in stead of negative values like opposing against the bio-industry) and is in hands of private ownership (and hence criteria are not embodied in the law) it seems that a process of continuous upgrading is more likely. When the organization, besides setting norms and controlling them, uses 'artifacts' like symbols or brands, that strengthen the sense amongst farmers that they belong to a specific group, these farmers will have a more positive and active attitude towards the CCO. On the basis of these findings, other code of conducts organizations may avoid pitfalls and maximize potential levels of animal welfare.