The factors influencing participation in both purchase of development rights and transfer of development rights farmland preservation programs are analyzed using data from a survey of agricultural landowners and from spatial data on individual farms collected using GIS for four Maryland counties. Generally, the likelihood of participation increases with farm size, growing crops, if a child plans to continue farming, eligibility and the share of income from farming. Landowners closer to the nearest city were less likely to join. Survey information about landowner characteristics and local selection committees may aid in targeting efforts.