Fred Berry had his middle name legally changed to "Rerun."
According to writer Eric Monte, ABC had originally planned to do a TV version of Cooley High. After a poorly received pilot, ABC retooled it completely; "What's Happening!!" was the result.
In the initial draft, the role that became the character "Rerun" was going to be a skinny white kid.
Mabel King wanted the Thomas family to have a mother and a father (on the air Roger and Dee's parents were divorced, and their father remarried in 1977 and was not seen again). The producers' refusal contributed to her decision to quit her role in 1978. King was also unhappy with her reduced role in the series.
The character 'Dee Thomas' was ranked #5 in TV Guide's list of "TV's 10 Biggest Brats" (27 March 2005 issue).
Fred Berry and Ernest Thomas walked off the show during the second season demanding more money and better dressing rooms. Their demands were met. After the third season, Berry and Thomas convinced Haywood Nelson to join them in another walkout demanding more money. Even though the show ranked 29th in the 1978-1979 season, ABC canceled it rather than deal with their demands.
In reality Haywood Nelson is 10 years younger than Ernest Thomas, and 9 years younger than Fred Berry.
According to Haywood Nelson, he was in a relationship with Debbi Morgan, who played the recurring role of Diane. But Nelson said that he was not mature enough at the time to commit to their relationship.
Eric Monte sued the producers claiming that he did not receive proper credit as the creator of the series. Monte only received a credit at the very end of the closing credits that read "Suggested by the American International picture Cooley High written by Eric Monte". He also claimed that he was promised a credit as a producer. He received an out-of-court settlement.
For the first two seasons, Haywood Nelson commuted from his Garden City, New York home to Los Angeles to work on the series.
During the making of the series, Danielle Spencer was involved in a car accident which left her in a coma for a few days. When Spencer began work on the series after the accident, she had to do most of her scenes sitting down to avoid physical exertion, and altered her hair style and bangs to cover up damage to her forehead from the accident.
The Lockers, who played The Rockets, were a dance group of which Fred Berry was a member. The group was formed by Toni Basil and Don Campbell.