Despite being eligible for use in any neighborhood, housing choice vouchers tend to be redeemed in low-opportunity neighborhoods. This paper investigates how landlords contribute to this outcome and how they respond to efforts to change it. We leverage a policy change in Washington, DC, that increased voucher rental payments only in high-rent neighborhoods. Using two waves of a correspondence experiment that bracket the policy change, we show that most opportunity landlords screen out prospective voucher tenants, and we detect no change in average screening behavior after a $450 per month increase in voucher payments. In lease-up data, however, enough landlords do respond to increased payments to equalize the flow of voucher tenants into high-vs. lowrent neighborhoods. Using tax data and listings from a website specializing in subsidized housing, we characterize a group of marginal opportunity landlords who respond to higher payments. Marginal opportunity landlords are relatively rare, list their units near market rates, operate on a small scale, and negatively select into the voucher program based on hard-to-observe differences in unit quality.