The present study examines the optimal recycling rate for municipal solid waste. First, an optimal control model is developed to describe the waste accumulation phenomenon. The physical costs of recycling, the social costs of landfilling, and consumers’ environmental preferences are accounted for, and optimal recycling and landfill disposal paths over time are derived. The need for landfill space is implicitly determined given the amount of waste generated and the costs and constraints on waste management alternatives. Second, an optimal solution is simulated using waste disposal data from the Helsinki region in Finland. The benefits from recycling are included in the simulation using the results of a recent contingent valuation study. The results of the present research suggest that mandates for achieving 50% recycling in municipalities are not far-fetched and are both economically and environmentally justified.