Water pollution in urban environments has continued to decline despite efforts to decrease non-point source pollution. One strategy has been to recommend the use of native prairie plants in lieu of lawns under the premise that their deep root systems encourage water infiltration thereby reducing runoff. Previous studies have indicated the amount of antecedent soil moisture partly dictates runoff volumes during precipitation events. We conducted two studies to determine the effects of vegetation type on antecedent soil moisture and surface water runoff resulting from natural precipitation. Since many urban areas are routinely reconstructed, necessitating new turf establishment, a field study was developed to compare the effects of young turfgrass and prairie vegetation on soil moisture. In November 2002, plots were seeded with either Kentucky bluegrass or a commercial prairie mixture of forbs and grasses. Since prairies mature over several years, a second study was developed to compare soil moisture differences of turf and mature prairie. In July 2003, segments of a 9 year old prairie were stripped and replaced with a mature Kentucky bluegrass sod to compare soil moisture between vegetation types. A randomized complete block design was used for both studies. Time domain reflectometry was used to continually monitor moisture content in the upper 15 cm of soil. Mature prairie maintained soil moisture similar to Kentucky bluegrass established from sod. Early-stage prairie, however, typically maintained greater soil moisture compared to similarly-aged Kentucky bluegrass turf. The faster reduction in soil moisture in a Kentucky bluegrass turf compared to your prairie indicates turfgrass may be more effective at reducing urban runoff due to a greater capacity for infiltration. Once a prairie matures there is no practical difference between prairie and turf vegetation effects on soil moisture.