During the mid-1970s, the US embarked on a modest but highly focused effort to demonstrate an aircraft possessing a very low radar signature and sufficient performance to have operational utility. Known as Have Blue, the project was highly successful and led to the F-117 A. This paper discusses issues associated with reducing radar signature to very low levels (levels that are “tactically meaningful,” e.g., capable of defeating realistic threat systems). Radar phenomena and the concept of radar cross section (RCS) are briefly summarized and RCS reduction techniques as they were applied to Have Blue are described. RCS reduction considerations and techniques pioneered by Have Blue have become an integral component of the combat aircraft design process over the past two decades.