There is widespread use at this time of various tax incentives (1, 3, 5, 7, 8, 16) to stimulate property owners to maintain agriculture or open space on their land. The success of such programs will depend to a great extent upon the monetary incentives that they provide to property owners. The existence of preferential treatment in the taxing system prior to the implementation of preferential farmland assessment legislation has been proven by several authors (2, 4, 12). Such de facto preferential assessment has been noted in areas other than agricultural land (13, 20). This type of preferential assessment may be innate to the system that assessors use in determining the value of farmland (17, 18), or it may be the result of a conscious effort on the part of the assessing authorities to give preferential assessment to farm land and open space (15). The following quotation is taken from the Lehigh-Northampton County Joint Planning Commission Study, “Act 515 in Lehigh County – A Follow-Up Study”.