Comfort air conditioning is largely an American development which grew out of the need for the control of humidity levels in industrial processing as early as 1904. Between its earliest appearance and the coming of age of residential air conditioning after 1945, this promising industry experienced a forty-year long adolescence in which it struggled to define and develop a market for its product. This talk takes up the discussion of how current social expectations about air-conditioned comfort have historical roots in this formative period, when expert advice, commercial interests, and consumer practice gave shape to an evolving technology. Several issues entered the public debate early and continue to be relevant. What relationship do we hope to maintain between the natural environment and the built environment? How do we define comfort and why do we bother? How do we structure the dialogue between experts and consumers? And, my favorite, how do we understand our technical past? Gail Cooper is author of ”Air-Conditioning America: Engineers and the Controlled Environment 1900-1960,” Johns Hopkins University Press, 1998.