Her photography addressed such social issues as homelessness, loneliness, drug addiction, and prostitution. She worked primarily in black and white. She described her approach to her subjects: "I’ve always felt that children and teenagers are not "children," they’re small people. I look at them as little people and I either like them or I don’t like them. I also have an obsession with mental illness. And strange people who are outside the borders of society." Mark also said, "I’d rather pull up things from another culture that are universal, that we can all relate to….There are prostitutes all over the world. I try to show their way of life…" Mary Ellen Mark - March 20, 1940 - May 25, 2015