Joslin was born in Melrose, Mass. in 1946 and spent his youth in Lynnfield and Cumberland. He earned his B.A at the University of New Hampshire in 1972, and his MFA four years later from the Rhode Island School of Design. In addition to his filmmaking, he taught at Hampshire College and at the University of Southern California. Joslin began making short films in 8mm, at the age of 14. His work included Blackstar: Autobiography of a Close Friend (1976), a film about coming out and growing up as a gay filmmaker, and Architecture of Mountains (1979), a dream-based experimental film. In 1981, he chose to leave academia to try to make it as a writer/director in Hollywood. He teamed with Selise E. Eiseman forming the Primary Colors Company while working as an uncredited casting assistant for Zoetrope Studios. When Joslin and his long-time lover Mark Massi were both diagnosed with AIDS, he decided to shoot a video diary: Silverlake Life: The View From Here (co-directed by Peter Friedman, 1993). He died on July 1, 1990, in Los Angeles.