Certification schemes that aim to provide an assurance on animal welfare have been developed in many countries but there is no internationally agreed mechanism for recognising the equivalence of animal welfare schemes. The lack of standardisation is a complication in international trade as the lack of clarity may impede demand for products from animals reared according to specified levels of welfare. An important first step is to define a credible best practice framework for animal welfare certification schemes that could apply in any country. Schemes may aim to provide assurance on minimum levels of welfare or may also aim to promote welfare improvement within their scheme membership. It is proposed here that certification schemes wishing to make animal welfare claims could adopt a scheme level continuous improvement approach, as already used in quality and environmental certification schemes, to promote improvement at a farm level. It is suggested that this can be achieved by using the following four generic principles. Firstly the scheme can operate a management system that co-ordinates scheme activities which actively promote improvement in animal welfare within participating farms. This management system should include the following generic steps: plan (establish the objectives including desired outcomes, scheme requirements and monitoring processes), do (implement scheme inspection systems and support structures), check (measure and monitor the process and results) and improve (take action to improve performance). Secondly the scheme should develop progressive resources and outcomes requirements that comply with relevant legislation, encourage the provision of opportunities valued by the animals, promote farm level continuous improvement in important welfare outcomes and require innovation not to compromise welfare goals. Thirdly the scheme should target its assessment and support resources on important welfare concerns. Activities should include assessment of relevant welfare requirements and outcomes, promoting interest amongst farmers in their management, ensuring technical advice is available and insisting on remedial action for those farmers with consistent poor outcomes. Finally by taking an evidence-based, participatory and transparent approach the scheme should also embrace external scrutiny and involvement.