A simple and reliable technique is used to describe the selectivity for removal of exposed and unexposed resist for various developer systems. The technique requires no special apparatus. All that is necessary is a method of exposing photoresist and measuring resist thickness, although the method is simplified if a step and repeat exposure system is used. Measurements of resist thickness are made after resist development over an incremented span of exposures. The logarithm of exposure vs. retained resist thickness curves give excellent prediction of sidewall profiles. A contrast parameter, Y, can be calculated for a particular process giving a figure of merit to compare processing methods. Information concerning developer activity can be extracted from two exposure thresholds; Ei, the induction to removal, and E0, the complete removal of photoresist. Further, this technique pertains not only to develop processing, but to any part of the photoresist process which has an impact on contrast. This paper reports on the use of the technique to characterize and compare two positive resist developers: One that is formulated for high resolution and high contrast (Shipley Microposit MF-314, CD31) and one that is formulated for high throughput and aggressive process performance (Shipley Microposit MF-312, 3:2 dilution). The developers have been evaluated for the three common modes of resist development (immersion, spray, and puddle) and at differing temperatures, spin speeds, nozzle pressures, and with and without a post exposure bake. It is demonstrated that this technique of evaluation delineates significantly between develop systems as regards contrast, provides a firm basis for process optimization aimed at high resolution, and advances understanding of the dynamics of positive resist development.