Originally written for the October 1970 meeting of the Institute of Management Sciences, this paper describes the Landlord Reinvestment Model, a computer program that prepares financial analyses of alternative assistance treatments for buildings requiring repairs to meet New York City housing code standards. It enables estimation of the level of City assistance needed to induce a landlord to reinvest in his property through performance of required repairs, payment of debts, and provision for adequate future maintenance. The model was designed for the Problem Buildings Evaluation and Treatment System, an experimental unit in the New York City Housing and Development Administration formed to combat the loss of houses from existing inventories. The dimensions of that problem: between 1965 and 1968, 114,000 housing units were lost to New York City, most abandoned as financially hopeless by landlords. 16 pp. Ref.