||Arthropod abundance and vegetation composition were studied in four 0.25- ha grassland plots on Nantucket Island, Massachusetts. Treatments included burning in April, burning in August and mowing in August, in 1983 and again in 1985. Cover and frequency of plants in 1985 was little changed from pretreatment levels. Arthropods were sampled in July, August and September of 1985. In the April burn plot, numbers of Arachnida were lower and Orthoptera were higher throughout the season than in an untreated reference plot. Other orders showed little consistent change. In the August burn and mow plots, total numbers of arthropods, especially Hymenoptera, Orthoptera, and Lepidoptera, were higher early in the season in 1985 compared to the reference plot. Following treatments in August, most orders declined in abundance compared to the reference plot, with the exception of the Homoptera, which increased.