The purpose of the study reported here was to evaluate a long path laser air pollution monitor developed for the U.S. Environmental Protection Agency (EPA) by the General Electric (GE) Company. The monitor was known as ILAMS (Infrared Laser Atmospheric Monitoring System) and designed explicitly for measuring the ambient ozone concentration. The evaluation program was conducted in both the laboratory and under field conditions. In addition to the evaluation several system modifications were carried out such as, the addition of a beam steering system, the addition of a He-Ne laser alignment system, and various improvements in laser alignment techniques. The field study portion of the evaluation was carried out as a part of the North-East Oxidant Study (NEROS) and was conducted during the month of August 1979. The experiments conducted, the modifications made, and the problems identified are completely described in the report.