Mindy Cohn wasn't an auditionee for the show. When the producers visited a girls' school to see how the girls interacted, she was a social magnet just being herself, and they created Natalie based on Cohn. She was then tested in the role.
Kim Fields was only nine years old when she started playing Tootie, who was supposed to be twelve. In an effort to make her appear taller (and older) her character was always in roller skates for the first year of the show.
Originally, the premise of the series was that Edna Garrett, the housekeeper on Diff'rent Strokes (1978), became the headmistress at the school that Kimberly Drummond (Dana Plato) attended. But after the pilot episode, the producers decided to keep Plato on Diff'rent Strokes (1978) and there was never any mention of Kimberly being a student at Eastland again.
When she left after the seventh season, Charlotte Rae recommended Cloris Leachman to replace her. Rae and Leachman were classmates at Northwestern University and were roommates when they were young struggling actors in New York City.
Midway throughout the sixth and seventh seasons, Charlotte Rae had missed several episodes due to her health problems. This led her leaving the show at the end of the seventh season, although she did make two more guest appearances at the beginning of the eighth season.
During the final season, producers made a controversial decision to shake things up by having one of the girls lose their virginity. Initially Blair was to be the character, but Lisa Whelchel protested it as the idea went against her deep seeded Christian beliefs. Whelchel further explained she didn't want her character to be seen as such an improper role model for the show's young viewers. Mindy volunteered to have her character lose her virginity instead because writers felt it was time for one of the characters to experience this and Natalie was in a long term relationship so Mindy felt it made sense for it to be her and the writers agreed.
During the last season, David Spade was in an episode that was supposed to be turned into a spin-off series called "Big Apple Blues" about college roommates living in New York City, but it never materialized.
The character Jo was inspired by then NBC Chief Fred Silverman after he had seen the film Little Darlings. He felt a streetwise scholarship student would contrast well, and add conflict, against the rich, spoiled Blair character.
If the show had returned for a tenth season, the producers had planned for Blair to buy Eastland to save it from being closed down. However, those plans never came to fruition due to the series' cancellation.
During the course of the show it was revealed that Mrs. Garrett and Beverly Ann hailed from Appleton, Wisconsin; Blair and Natalie hailed from Manhattan; Jo hailed from the Bronx, and Tootie from Washington D.C.
Eastland was located in the Westchester County town of Peekskill, New York, which is located roughly forty miles north of Manhattan. With a commute of less than forty five minutes to Manhattan, this explains the relative ease in which Manhattanite Blair and Bronx-born Jo are able to go home as often as they do, and also helps to explain the continuous interaction between the Drummond family and Mrs. Garrett after her departure from their household.
For the second season, the entire concept and plot of the show was changed from a large boarding house of several young girls, to a tighter knit group of older adolescent women. This was done since the producers felt that a plot change from comic relief to serious adult issues would help boost ratings. The cast of girls was reduced to only four, including the new character of "Jo".
Even though Kim Drummond never ended up at Eastland like the original plot of the series had planned, the show still was connected to the "Different Strokes" universe with Mr. Drummond and Arnold making a few guest appearances. In addition, some of the Facts Of Life characters, mostly Tootie, made crossover appearances on Diff'rent Strokes in which they were seen visiting Kimberly.
During the 9 year run of the series the producers made multiple attempts to Spin Off "The Facts of Life" by producing 6 Back-Door Pilots that were to serve as possible pilots for a new series. In chronological order the episodes are "Brian and Sylvia" "The Academy" "Jo's Cousin" "The Big Fight" "Big Apple Blues" and the Two part series finale "The Beginning of the End" and "The Beginning of the Beginning" In the end none of these attempts were successful.
In the first season, there were seven students in the main cast. After the first season, the producers decided to drop four characters from the main cast: Molly Parker (Molly Ringwald), Cindy Webster (Julie Anne Haddock), Sue Ann Weaver (Julie Piekarski) and Nancy Olson (Felice Schachter). But Haddock, Piekarski, and Schacter continued to appear occasionally until the third season.
The character of Blair, was originally conceived as a down-home charming Texas girl. However, during her audition for the role Lisa Whelchel read several of Blair's lines sarcastically. Producers were so impressed by Whelchel's audition that they re-wrote the character to be that of a self-involved New York blue blooded socialite.
Blair's Parents were played by Actors who had longtime Soap Opera Careers, Nicholas Coster and Marj Dussay. In addition, Jo's Mother was played by Claire Malis Callaway, who also a veteran Soap Actress.
Blair was initially portrayed as the "bad girl" of the series. When the show was retooled for the second season and Nancy McKeon joined the cast, Jo took over the "bad girl" persona. At the same time, Blair was transitioned into her more familiar vain, spoiled rich girl image.
When Diff'rent Strokes became an instant hit, it was also at the time one of NBC's few viable series. As a result,Fred Silverman believed that the network could capitalize from a Diff'rent Strokes spin off. It was ultimately determined that Charlotte Rae had the proper ability and experience to be able to carry her own series. In addition, it was felt that since Mrs. Garret wasn't central to Diff'rent Strokes her departure wouldn't negatively effect the series.
Over the course of the series, Eastland was shown having four Headmasters, Mr. Bradley, Mr. Harris, Mr. Parker and in the final episode, Blair. In addition, the Diff'rent Strokes episode which served as a Pilot for the series featured a Headmaster named Mr. Crocker.
Originally the school was to be called Eastlake Academy, a take on the name of Westlake Academy, a LA area school that was said to be the inspiration for the show. The Eastlake name was used in the Diff'rent Strokes episode which introduced the series.