The Day & Zimmermann Group delivers managed services that include government and defense contract support, power plant maintenance and modification, technology staffing, engineering, construction, validation services and security services. Founded in 1901, the company specializes in staffing services to municipal, state and federal government agencies and the defense industry. Day & Zimmermann provides munitions products and services to foreign governments approved by the United States. The Day & Zimmermann Group is headquartered in Philadelphia, and maintains a location in Hawthorne, Nev.