River finally got work in the film "Explorers". River worked with Jason Presson and Ethan Hawke, who were kids of his own age. Finally, Rio could socialize with kids of his age. The problems with his vegetarianism went on, but this time John let Rio to wear leather to make things easier for everyone.
Rio was very sad to leave his new friends when the film finished:
"River was weeping and crying when Ethan got the bus to leave to go home to New Jersey" says Joe Dante, director of the film.
After the film in 1985, Iris Burton got an audition for him with Rob Reiner for a role in the film "Stand By Me". River did the audition along with 300 other youngsters, and he was the first one cast for the film.
During this film Rio became very good friends with the others, especially with Corey Feldman. He learned to smoke and took marijuana for the first time. He also lost his virginity with an eighteen-year-old friend of the family. Rio asked his parents for their blessing, and they gave it to him. Moreover, they decorated a tent for them.
"A very strange experience"-River declared.
This film made River a star. His face was in all the magazines,he received thousands of letters from fans asking for autographs, and everybody told him that he was going to be a great star,... hard things for a shy fifteen-year-old boy to handle.