Cold storage is the standard recommended method for prolonging the usable life of photographic materials. The use of cold storage facilities has been an important addition to the techniques and operating procedures of museums and other organizations charged with the long-term storage of photographs. While the value of cold storage is universally accepted, the techniques and pitfalls of operating a cold storage facility are less well known. Cold storage units are a complex assemblage of mechanical equipment to chill and dehumidify the air, while also removing harmful gases commonly found in an urban environment. The planning, funding, construction and operation of a large, walk-in cold storage unit requires both extensive time and detailed working knowledge by the staff assigned to the facility. The Smithsonian Institution's Office of Photographic Services has operated a photographic cold storage facility since 1982. This case study reviews the lessons learned in the construction and more than two decades of experience in the daily operation of this facility.