The United States has traditionally lagged behind Europe in the adoption of voluntary or legislated standards for the care and treatment of animals on farms. US federal legislation of farm animal practices is minimal, confined to aspects of livestock transport and slaughter. Although some of the livestock and poultry producer (commodity) groups wrote guidelines, codes of practice, or statements regarding the humane treatment of animals in the 1980s, these were usually very general statements of current industry practice, developed with little consultation with independent experts and involving no mechanism for encouraging or ensuring compliance by producers. However, this has changed dramatically in the last few years, with an increasing trend among US retailers to require their suppliers to adopt minimum animal welfare standards. The major chain restaurants and supermarkets are working through their trade organisations, the National Council of Chain Restaurants and the Food Marketing Institute respectively, and with the commodity groups, to develop a uniform set of standards and a national auditing program. Standards and auditing programs have already been approved for dairy cattle, laying hens and meat chickens, and for slaughter, including ritual slaughter (kosher and halal). The process of setting auditable standards is complicated by the lack of legislative underpinning, the scope of the auditing that will be required because of US farm sizes and the large distances between farms, and the varying levels of expertise of potential auditors. For these reasons, ‘engineering-based’ auditing criteria that are relatively easy to measure and to standardise are more common. There are both strengths and potential weaknesses of retail-driven rather than legislatively driven animal welfare standards. Regardless, the recent changes in the US possibly pave the way for increasing dialogue between Europe and the US on farm animal welfare issues.