One Day at a Time

Classic 1970s sitcom created by Norman Lear, focusing on an Indiana woman and her two daughters moving to Indianapolis to begin life anew after a rocky divorce, and the trials they face adjusting to new life. Oh, and their Casanova Wannabe super named Schneider joins in the wacky adventures.

The show is probably best remembered nowadays for its Ear Worm theme song, a preponderance of Very Special Episodes, and the offscreen travails of cast member Mackenzie Phillips.

Tropes used in One Day at a Time include:

Acting for Two: In a 1983 episode, Pat Harrington played not only Schneider, but also Italian immigrant Guido Panzini, a character he had created for The Jack Paar Show some thirty years earlier.
Big Brother Instinct: And/or a sort of surrogate father complex -- Schneider regarding Julie and Barbara, especially in the later years of the series.
Big OMG: Ann Romano turns it into a Catch Phrase.
Bob Haircut: Julie.
The Bus Came Back: Julie, after Mackenzie Phillips' well-documented drug problem and subsequent rehabilitation. Then she got put back on the bus when it didn't take.
The Couch
Dawson Casting: Notably averted with Valerie Bertinelli and Mackenzie Phillips, who were almost exactly the same ages as their characters.
Embarrassing Middle Name: Dwayne Florenz Schneider.
Fangirl: Barbara, for Elton John, in the earlier seasons.
Hey, Let's Put on a Show: The first time it was to save their building; later it continued happening for murkier reasons. And as the cast kept gaining singers and dancers, the shows got more elaborate.
Landlord: Schneider
Porn Stache: Schneider again.
Put on a Bus: Several characters from the early seasons, including Ann's divorce-lawyer-cum-boyfriend David and cocktail-waitress neighbor Ginny Wrobliki. Mackenzie Phillips, too, in a later season when her drug problems grew too severe, although when she cleaned up a few years later, The Bus Came Back. Unfortunately she didn't stay clean and got put back on the bus for good.
Rapunzel Hair: Barbara, in the first few seasons, had long, straight hair reaching down below her waist.
Reunion Show: In February 2005.
Tomboy and Girly Girl: Julie and Barbara respectively. Usually.
Unperson: Insofar as someone who never appeared on the show can become one: in the first few seasons, Barbara was a rabid Elton John Fangirl, to the point of doing a number in Elton costume for one of the "musical" episodes. Then Elton revealed his sexuality, and suddenly Barbara never mentioned him again. (Barbara's obsession wasn't entirely stalinized from the show, though; a clip of her dressed as Elton remained in the opening credits until the end of its run.)
Visit by Divorced Dad
Vitriolic Best Buds: Kinda sorta between Ann and former rival Francine, after the two of them teamed up to open their own advertising agency.