Development of the U.S. Army's 1500-shp advanced technology demonstrator engines was initiated in 1967. Presented are several lessons of a technical and nontechnical nature learned from the program. Several problem areas encountered are highlighted and analyzed. Reflected is the need for standardization within the industry of methods of bookkeeping component efficiencies and of conducting engine performance analysis. Scheduling, development approach, and instrumentation experiences and requirements are also discussed.