Back in 1975, ABC designed a sitcom around a standup comedian named Gabe Kaplan. He had no acting experience at all. He was to play an inner-city high school teacher to a gang of slackers. Where did that idea come from? From Kaplan’s own experience.
1. THE SERIES WAS INSPIRED BY GABE KAPLAN’S STAND-UP ROUTINE.
Kaplan was a star player on his high school baseball team and dreamed of someday playing in the major leagues. When he tanked at the San Francisco Giants’ spring training camp, he headed back east and took a job as a bellman at a resort hotel in Lakewood, New Jersey. After watching the touring comedians who performed there for a few months, he decided to take a stab at stand-up. He eventually developed a routine based on his experiences in a remedial class at Brooklyn’s New Utrecht High School and took his act on the road. Fellow Brooklynite Alan Sacks, who was working in Los Angeles as the producer of Chico and the Man, caught Kaplan’s performance at The Comedy Store at the urging of Freddie Prinze, and a TV sitcom pitch was born.
2. ANY RESEMBLANCE TO REAL PERSONS WAS STRICTLY INTENTIONAL.
Vinnie Barbarino (originally called “Eddie Barbarini” in the pilot script) was a combination of two real-life people: Kaplan’s fellow Sweathog Eddie Lecarri, and a tough kid named Joey Caluchi that Alan Sacks knew in junior high school. Freddie “Furdy” Peyton inspired Freddie “Boom Boom” Washington, and “Epstein the Animal” (as he was known at Kaplan’s alma mater) was transformed into the half Puerto Rican Juan Epstein at the suggestion of ABC’s then-head of programming, Michael Eisner. Only Arnold Horshack’s character retained his real-life counterpart’s name … although the original Arnold was so obnoxious that by the fourth grade, according to Kaplan, even the teachers began calling him “Arnold Horsesh**.”
So that was the genesis of Welcome Back, Kotter. You’ll find out much more, like casting decisions and the rise and fall of the series, in a trivia list at mental_floss.