The impressive growth in land conservation by the private sector, primarily by land trusts, has resulted from a number of policies that subsidize such activity. These include federal income and estate tax benefits, and state income and property tax benefits. We model the equilibrium in the private land conservation market and the social welfare maximization problem of the government. We estimate the supply of conservation easements in the San Francisco Bay Area counties. Our results show that conservation easements are own price inelastic, but nevertheless are sensitive to the opportunity cost of land. For a simultaneous equation model, the spillover effect of easements on the value of other properties is found to be positive and significant. A possible equity implication is the barriers to entry facing low-income individuals in the housing market.