Jaimee Foxworth originally played the role of the youngest Winslow child, Judy. The combination of her character having little to do and Foxworth's request for a salary increase led producers to simply write her off the series. Later episodes revised the show's history so that Judy never existed and the only two Winslow children were Eddie and Laura.
Jaleel White played eight characters during the series. Of course, his original character is Steve Urkel. He also played his female cousin Myrtle Urkel a few times and male cousin Cornelius Eugene Urkel (or "OGD: Original Gangsta Dawg"). He also provided the voice of his invention Urkel-Bot twice. The remaining are Steve's alter-egos (in order of reverse length of appearance): Stefan Urquelle, Bruce Lee, Elvis Presley, and Albert Einstein.
The character of Steve Urkel was named after a friend of one of the producers, and was only supposed to appear once. However, the audience's response was so overwhelmingly positive that the producers decided to make Urkel a regular character. The character spawned a series of merchandise including a talking doll, trading cards, posters, books, lunch boxes and T-shirts. It even had its own limited edition cereal.
Although the interiors of the Winslow house were stage sets, the exterior of the house was taken from a real-life house located on Wrightwood Ave in Chicago, and (as of 2009) still exists as it appears during the series run.
The theme song for the first five episodes was "What a Wonderful World" by Louis Armstrong. The series' more familiar theme, "As Days Go By", was first used in episode six. The original ABC broadcasts, as well as the later airings on ABC Family, for episodes from the first three seasons use an extended version of the "As Days Go By" theme accompanied by clips from selected episodes. Syndication edits of "Family Matters" feature the abbreviated version of the theme used in season 4 through 6. On the ABC Family airings, there is an extended opening sequence, which presumably has not been used since the series originally aired on ABC.
When ABC delayed making a decision to renew the show for a ninth season, CBS made a deal with Warner Bros. Television to renew the show for a ninth season, which would be its last. The show's producers hoped for a 10th and final season on CBS, but the ratings for the 1997-98 9th season were so bad that the network ended up canceling the show and airing the series finale with no fanfare during the summer season. In a nod to the stillborn plans to have Steve and Laura get married in a 10th season, the series finale did have them getting engaged. JoMarie Payton decided to leave the show when it moved networks from ABC to CBS because she didn't like how the show overemphasized the Steve Urkel character. Payton agreed to appear during the first half of the ninth season, after which she was replaced as Harriette Winslow by Judyann Elder.