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As the woody legume, <i>Prosopis glandulosa</i> (honey mesquite) has encroached into grasslands and rangelands in the southern Great Plains, USA, two grass species, C₄ shortgrass, <i>Buchloe dactyloides</i> (buffalograss), and C₃ mid-grass, <i>Nassella leucotricha</i> (Texas wintergrass), have increased in dominance. Occurrence of more productive C₄ mid-grasses and herbaceous diversity have declined. We measured effects of various combinations of spring clipping (to simulate cattle grazing) and summer and/or winter fire treatments on the stability of monoculture patches of these two grass species over an eight-year period, with the goal of reducing <i>Nassella</i> and increasing C₄ mid-grass cover. All fire treatments top-killed most <i>Prosopis</i> trees that subsequently resprouted. <i>Buchloe</i> cover declined in the No Clip + No Fire treatment but remained intact with clipping and/or fire. Frequent clipping reduced <i>Nassella</i> cover across all fire treatments. <i>Buchloe</i> encroachment into <i>Nassella</i> patches was greatest in the Clip + Alternate Season fire treatment. C₄ mid-grass cover increased to 15–25% in <i>Nassella</i> patches in several fire-only or Clip + Fire treatments; greatest gains were observed in treatments that included summer fire. In contrast, C₄ mid-grass gains were lower in <i>Buchloe</i> patches. These results suggest that C₄ mid-grass restoration was linked with treatments that reduced <i>Nassella</i> cover.