We investigated the use of sheep for controlling the spread of purple loosestrife in a wet meadow in upstate New York from June to August 2008. Changes in the purple loosestrife population and vascular plant community structure were monitored as a function of the grazing of two ewes, “rotated” through four “experimental” paddocks at 2- to 3-d intervals. Comparative data were collected in “reference” paddocks from which sheep were excluded. Purple loosestrife was heavily grazed and most plants did not flower in experimental paddocks. Purple loosestrife cover declined by 40.7% in the experimental paddocks but did not change significantly in the reference paddocks. After grazing, species richness was 20% higher in experimental than reference paddocks.