After the laser was first demonstrated in 1960, many American defense officials hoped it would become a revolutionary new weapon. At the Institute for Defense Analyses (IDA), a nonprofit advisory corporation contracted to the Defense Department, experts studied the possibility of using lasers to defend against nuclear-tipped ballistic missiles. A few academic consultants for IDA (among them physicists Nicolaas Bloembergen, Charles Townes, Keith Brueckner, and Norman Kroll) began to think about how to generate laser pulses of enormous power and propagate them through the atmosphere. Along the way, in a mix of classified discussions and reports, and through a series of important publications in the open literature, the consultants laid the foundations of a new field: nonlinear optics. Nonlinear optics is the science of the interaction between matter and intense light, and it became a major branch of physics in the 1960s. The field’s history calls for deeper consideration of the ways in which powerful institutions and the production of knowledge were joined in the Cold War era. Though nonlinear optics was every bit “Cold War science,” the conventional and widely used concept of “patronage” seems inadequate for understanding the origins and development of the field. A product of neither government contracts nor innovations in technology alone, nonlinear optics was fashioned by a close-knit and elite community of experts straddling the classified and unclassified domains. The field took its peculiar shape and content within this unique social space—the social world of the Cold War defense consultant.