Across the world, in nations from China to Cuba, this Thursday, June 1, will mark what's now widely known as International Children's Day. The purpose of such a day — some other nations mark it at different times throughout the year and the U.N. has Universal Children's Day in November — is to both celebrate the lives of children and remember the importance of protecting them so that they can fulfill the boundless potential that comes with being young.
In honor of that day, LIFE takes a look back through its 37 years of iconic photography to find images that capture the breadth of experience of children around the world. Funny or serious, cute or moving, happy or sad, the kids shown here illustrate in their own ways an element that makes childhood uniquely special. They may be small, but their inner lives, as captured on film by LIFE’s expert photographers, are anything but.