Sometimes figuring out who's captured in your old black-and-white photos, and when and where those pictures were taken, is like playing a game of chance. Try to recall what Grandma said about it, guess at a year—and the photo might or might not be Great-grandma Clara and her sister, Imogene.

Mystery photos—the ones with no names, places, dates or events to go with the faces—inspire all kinds of questions. Who are those people, when were they alive and what can they tell you about your family history? Today's your lucky day: Heed these 13 hints to match up the faces in your photographs with the people, places and dates on your family tree.