Children playing baseball in a tenement playground, USA, c 1913.

Photograph taken by Lewis Wickes Hine (1874-1940). Trained as a sociologist, Hine used photography as a documentary tool to inspire social reform. For instance, his ground-breaking documentation of child labour was instrumental in the passage of child labour laws. Many of his most famous images show the conditions of immigrant life in the USA, and they reveal both the horror of exploitation and the dignity of work.