Although flow cytometers have become indispensable to researchers in many areas of biology and medicine who study the normal and abnormal behavior of cells, acquisition costs of apparatus remain high. Recent advances in laser, reagent and electronic technology now make it possible to build multiparameter flow cytometers using inexpensive diode and solid-state laser sources, with digital signal processing electronics, which can match, and in some cases, surpass the performance of existing instruments for a fraction of the price. This project will develop and test a low-cost flow cytometer, and evaluate optical and electronic approaches to improving performance of such instruments. PROPOSED COMMERCIAL APPLICATION The apparatus to be developed should make an important technology available to hundreds of laboratories not now able to afford it.