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Leafy spurge (Euphorbia esula L.), first introduced in North America in the 19th century, was found in North Dakota in 1909, and was considered a threat to rangeland in the Great Plains as early as 1933 (Hanson and Rudd 1933). The weed currently infests large amounts of untilled land in the Plains and Mountain states. Once established on untilled land, the weed spreads quickly, displacing native vegetation. Leafy spurge has unique characteristics that give it a competitive advantage over most native plants and provide it with natural defenses against cattle grazing. Leafy spurge can create serious economic losses for land owners and ranchers. Current control technologies are ineffective in eradicating established infestations. Although leafy spurge can be controlled through chemical, biological, and cultural methods, each control approach has limitations in its applicability and effectiveness in treating all leafy spurge infestations. However, many of the constraints prohibiting herbicides, tillage, and biological controls (i.e., prohibitive expense, unsuitable land, and physiological barriers) do not appear to eliminate sheep grazing as a possible control. Grazing with sheep and goats, while known to be effective in controlling leafy spurge since the 1930s, lacks widespread adoption (Sedivec et al. 1995; Sell et al. 1998). Many questions remain regarding the economic feasibility of using sheep to control leafy spurge. A goal of this study is to help determine how sheep grazing could fit into an integrated pest management approach to control leafy spurge by providing economic information for land owners to use in assessing their long-term control strategies. (source introduction)