Systems developers and researchers have long been interested in the factors that affect software development productivity. Identification of factors as either aiding or hindering productivity enables management to take steps to encourage the positive influences and to eliminate the negative ones. This research has explored the possibility of developing an estimable model of software development productivity using a frontier estimation method. The approach taken is based upon output metrics for the entire project life-cycle, and includes project quality metrics. A large number of factors potentially affecting software maintenance productivity were included in this initial investigation. The empirical analysis of a pilot data set indicated that high project quality did not necessarily reduce project productivity. Significant factors in explaining positive variations in productivity included project team capability and good system response (turnaround) time. Factors significantly associated with negative variations in productivity included lack of team application experience and high project staff loading, The use of a new structured analysis and design methodology also resulted in lower short term productivity. These preliminary results have suggested a number of new research directions and have prompted the data-site to begin a full scale data collection effort in order to validate a model of software maintenance productivity.