For those who don’t know Mary Ellen Mark personally, the notion of one of the world’s premier documentary photographers hosting a Christmas party for dogs might sound downright weird. But for the past decade, Mark has opened the doors of her New York City studio to throngs of canines.

In the last ten years, Joe Manning has tracked down the life stories of more than 350 child laborers in Lewis Hine's documentary photography for the National Child Labor Committee.

Of the countless letters written to LIFE magazine after JFK's assassination, one in particular -- from a second-grader -- seemed to capture not only a nation's loss, but something of an era's innocence.

On Veterans Day, LightBox presents rare, vibrant color autochromes documenting the soldiers and battles of the First World War.

Terror often stems not from the unknown, but from something familiar that has been subtly -- but unmistakably -- transformed. This certainly helps explain why Finnish photographer Perttu Saksa's series of masked and chained monkeys is so unsettling.