The history of clean rooms is strictly modern. Its growth parallels the development of precision manufacturing industry and the understanding of how contamination reduces yields and degrades performance of product. Pacing technology in measuring airborne, liquid borne, surface, and chemical contaminants created a "leap-frog" type of progression with contamination control technology and the industries they both serve. This paper highlights a few of the key factors and events that have brought us to the current status. This, also, is described and some projections are made as to what the future of the industry might be.Units: I-P