For her book Geisha: The Life, the Voices, the Art, Cobb entered another world closed to outsiders, the geisha of Japan. She was also given special access to photograph inside a different sort of closed world, the ill-fated Gore presidential campaign of 2000.
Cobb has also photographed for the Day in the Life series of books and was a prime contributor to Vietnam Veterans Memorial: The Wall, Here Be Dragons, and The Way Home: Ending Homelessness in America. Her work was also featured in the book Women Photographers at National Geographic and its accompanying exhibitions.
Cobb received her B.A. in journalism and a master of art from the University of Missouri. She also received an honorary doctorate of fine arts from the Corcoran College of Art and Design in Washington, D.C. As a child, she traveled the world with her family and grew up in Iran. She now lives in Washington, D.C.