The availability of simultaneous independent approaches to parallel runways significantly enhances airport capacity. Current FAA procedures permit independent approaches in instrument meteorological conditions (IMC) when the parallel runways are spaced at least 4,300 ft apart. Arriving aircraft must be dependently sequenced at airports that have parallel runways separated by less than 4,300 ft, a procedure that reduces the arrival rate by as much as 250h. The need for greater airport capacity has led to intense interest in new technologies that can support independent parallel IMC approaches to runways spaced as close as 3,000 ft. This interest resulted in several FAA initiatives, including a Lincoln Laboratory program to evaluate the applicability of Mode-S secondary surveillance radars for monitoring parallel runway approaches. This paper describes the development and field activities of this program.