Extensive research has been conducted on the influence of earthworm activity on nitrogen dynamics in agricultural and forest soils. Similar research in urban soils is lacking. This study was conducted to describe differences in earthworm population densities, carbon content, and nitrogen availability in young and old urban soils. Earthworms and soils were collected from open turf in residential yards less than 10 years old, residential yards greater than 75 years old, and from under mature broadleaf trees in urban parks greater than 75 years old. Soils from each site were analyzed for bulk density, total carbon and nitrogen content, and for concentration of plant available nitrogen in the form of ammonium and nitrate. Average earthworm densities were significantly higher in urban parks (300 worms m^-2) than in young residential soils (35 worms m^-2). Populations in old residential soils (131.7 worms m^-2) were higher than in young residential soils, although mean differences were not significant. Total carbon and nitrogen contents were significantly lower in young residential soils (0.09 %N, 1.3 %C) than in old residential (0.19 %N, 2.6 %C) or urban park soils (0.22 %N, 2.9 %C). Earthworm density was positively correlated with percent carbon and nitrogen present in all soils. Earthworm density was negatively correlated with soil bulk density, with young residential soils having the highest bulk densities (1.5 g cm^-3) and lowest earthworm densities. Soil bulk density appears to influence the ability of earthworms to establish high population densities, at least within a decadal time scale. Earthworms, through their burrowing and casting activity, appear to stimulate carbon storage in older urban landscapes.