Assessments of ecosystem restorations are necessary to improve restoration practices and goals. Restoration assessments, whether quantitative or qualitative, are also a vital part of managing previously degraded ecosystems. This study examined some of the key structural and functional characteristics and processes of a tallgrass prairie restoration near Arlington, Wisconsin for 5 y, 19 to 24 y after beginning restoration from cultivation, including mean annual drainage, N and C leaching, soil organic matter, pH, extractable P and K, total N and C contents, above- and belowground net primary production, leaf area index, soil surface CO₂ flux and net N-mineralization. Total soil N and C contents of the prairie restoration were compared to other nearby prairie restorations, remnants and an adjacent agricultural field, all on similar soil, to determine the degree of change in ecosystem properties as a result of ecological restoration. Soil properties and processes and vegetation characteristics varied annually throughout the 5-y assessment period, but most soil properties showed no significant temporal trend. Only soil N content in the 0–30 cm layer increased significantly in the 5-y period, but the rate of N increase did not coincide with the rate typical of N inputs to a prairie. Results suggest that most soil properties have either already come to some equilibrium with the surrounding environment or their rates of change were too small to measure over 5 y. This study demonstrates the difficulties of ascribing changes in ecosystem properties to restoration. The spatial and temporal variability and slow rates of change make it difficult to discern differences between restored, disturbed and natural ecosystems.