Improved sustainability in farming is one of the main objectives of the European Union's new Common Agricultural Policy (CAP) for 2021–2027. In an exploratory study conducted with German farmers, we examine the adoption-decision process for a comprehensive farm sustainability management standard. The standard is rooted in scientific assessment systems and aims to achieve higher levels of sustainability in all farm production processes. Despite the growing political interest and increasing consumer demand for sustainable food, no such sustainability standard has as yet become established in Germany. Using a Delphi process, we analysed the main hindrances to its wider acceptance. Linking our results to the pre-decision stages of Rogers' innovation-decision model, we find that there is both a lack of any relative advantage of a sustainability standard and a lack of communication of the benefits, such as optimised processes and possible economic improvements. We also analysed both the importance and the optimal configuration of the various elements that make up the standard. Besides the obvious desire for higher product prices, the data basis underlying the sustainability assessment is identified as the most important factor of an optimised standard. Technical user support is another aspect of great concern to the farmers questioned, whereas the threshold values for farming regulation given in the standard appear to be of less significance to them. According to those surveyed, a standard would need to display a high level of compatibility with existing farm management practices, it must not be too complex, and it would need to promote its advantages so as to overcome its lack of trialability. Agricultural sustainability management could play a role in achieving the national emission and biodiversity targets of European member states, but only if they are accepted by a majority of practitioners. However, current German management standards need to undergo further development if they are to meet the needs of practitioners. Our findings can help all member states to structure their agricultural policies and promote the use of farm sustainability management. Further research should aim to improve standards and tools of agricultural sustainability management and render them compatible with EU funding policy.