In the Bolivian city of El Alto on a recent day, youngsters shout out the destinations of departing buses to lure passengers.
One of these barkers is 15-year-old Luis Canaza. He earns about 12 cents for every bus he fills.
Canaza says he began working at age 7, helping his parents sell tennis shoes. On weekends, he performs clown shows.
All told, an estimated 850,000 Bolivian children work. They sell food and clothes at outdoor markets. They mine silver and harvest sugar cane.