Forests patches and forest fragmentation were quantified for seven area municipalities within the Regional Municipality of York for the period from 1975 to 1988. This quantification made it possible to determine the extent of forest changes in space and time. In 1988, forest cover shrank to 30%–50% of its 1975 extent. At the same time, the number of forest patches doubled or tripled and mean patch size and the area of interior (based on a 100 m wide edge) declined indicating a high rate of forest fragmentation. Key words: development, fragmentation, remote sensing, forest