This paper covers one component of a research project aimed at exploring the sustainability of beef cattle production in South Dakota. In this exploratory research, farmers/ranchers who follow alternative "near-organic" production practices are being studied in relation to farmers/ranchers who follow "mainstream" production practices. The study is being accomplished through comparisons of four "matching" pairs of "near-organic" and "mainstream" case study farms/ranches, with the members of each pair being as similar as possible in size-of-operation, types of cattle, natural and economic resources, and overall farm management levels. The comparisons involve both physical and economic measures of production. To determine farmers/ranchers who follow production practices most consistent with "organic" certification standards, we developed a producer organic index (POI) system intended to reflect in single composite numbers the degree to which each cow-calf operator and each cattle feeder being studied follows "organic" beef cattle standards. We also developed producer sustainability indices (PSls) to reflect the degree to which the same producers follow more broadly defined "sustainable" beef cattle production practices. The indices are being operationalized with information provided by South Dakota cow-calf producers and cattle feeders who responded to recent mail surveys covering production management practices [see Taylor and Feuz (1992 and 1993) for reports of the overall survey findings]. In this paper, we first describe the conceptual basis underlying development of the sustainability/organic index number systems and the procedures followed in developing the systems. We then present the four index number systems developed: a PSI and a POI for each of cow-calf producers and cattle feeders. Finally, we conclude with a brief indication of plans for future research. In that connection, we solicit reactions of readers that can be considered in further development of the index measures.