Grocery retailing concentration in U.S. cities increased on average in 1982, continuing a long-term trend. The all-SMSA (Standard Metropolitan Statistical Area) average four-firm concentration level in grocery retailing rose to 58.3 percent in 1982, compared with 56.3 percent in 1977, the previous census year. These results were obtained from a special tabulation of the 1982 Census of Retail Trade, previously unpublished. The four-firm concentration level ranged from 27 percent in Appleton, WI, to 90.6 percent in Iowa City, IA, in 1982. Although concentration levels have generally increased since 1954, considerable diversity in concentration change of individual metropolitan areas (SMSA's) was found. This report analyzes grocery retailing market concentration in 1982, as well as changes in concentration from 1954 to 1982.