This paper has two main purposes: ( 1 ) to develop a method for measuring the extent and bias of technical change which involves the use of non-parametric production frontiers and does not require information on prices or factor shares; (2) to apply this method to individual farm data drawn from a sample of Illinois grain farms for the years 1982 and 1984. The results indicate that technical innovation is land using in nature and that the rate of technical change is related to the size of farm.