Gary Hack teaches, practices, and studies large-scale physical planning and urban design. He is the former dean of the School of Design, stepping down in 2008 after 12 years. Prior to coming to Penn, he was a professor of urban design at MIT, and a partner in the professional firm of Carr Lynch Hack and Sandell in Cambridge.

Earlier in his career, Professor Hack was head of planning for Gruen Associates in New York and directed the Canadian government's housing and urban development research and demonstration programs. He oversaw several large neighborhood demonstration projects and the redevelopment of urban waterfronts in a number of Canadian cities. He has also served as an urban design consultant for projects in Japan, Thailand, Taiwan, China and Saudi Arabia.

Professor Hack has served on the board of the Association of Collegiate Schools of Planning and the Planning Accreditation Board. He is a former chair of the Philadelphia City Planning Commission, is a member of the board of the William Penn Foundation, and is active in civic affairs in Philadelphia.

Professor Hack has prepared plans for over thirty cities in the United States and abroad, including the redevelopment plan for the Prudential Center in Boston, the West Side Waterfront plan in New York City, and a Metropolitan Plan for Bangkok, Thailand. He has also worked with smaller communities on urban design issues by preparing downtown plans for Louisville Kentucky and Knoxville Tennessee, downtown development guidelines for the center of Portland, Maine; design review manuals for Hendersonville and Germantown, Tennessee; and guidelines for the development of the entrance corridors and downtown of Charlottesville, Virginia. He was a member of the team that won the competition for the redevelopment of the World Trade Center in New York, and drafted the urban design guidelines for the project.

His research includes studies of urban design successes in the US, published as Lessons from Local Experiences, and an international comparative study of urban development patterns, published as Global Regional Cities.