It stars Bonnie Franklin as a divorced mother raising two teenage daughters, played by Mackenzie Phillips and Valerie Bertinelli, set in Indianapolis.

The series was based on Whitney Blake's own life as a single mother raising her three children (including future actress Meredith Baxter) after her divorce from her first husband.

[1] Divorced mother Ann Romano (Bonnie Franklin) moves herself and her teenage daughters, rebellious Julie (Mackenzie Phillips) and wisecracking Barbara (Valerie Bertinelli), from their home in Logansport, Indiana, to Indianapolis.

After David takes a job in Los Angeles, the show focuses on Ann's dilemmas as a single mother and career woman and the girls' growing pains, with Schneider becoming a more welcome part of the family.

Alex (Glenn Scarpelli), the orphaned son of Ann's deceased boyfriend Nick (Ron Rifkin), moves in, changing the dynamics in the female-dominated apartment.

Later in the series' run, Julie gives birth to daughter "Little Annie" Horvath (Lauren and Paige Maloney), Barbara marries dental student Mark Royer (Boyd Gaines), and Ann's mother Katherine (Nanette Fabray) moves nearby.

Like many sitcoms developed by Norman Lear, One Day at a Time often tackled serious issues in life and relationships, particularly those related to second-wave feminism, and can be considered an example of the "dramedy" (hybrid comedy/drama) genre.

[3] In an ironic twist, during the 1979–1980 season, Mackenzie Phillips was dealing with drug addiction and entered rehab in 1980, reflecting the Alcoholics Anonymous central sobriety saying, "One Day at a Time.

"[4] Stories depicting such events as weddings, births, and other important milestones frequently stretched over two-, three-, and four-part episodes.

Original cast member Richard Masur was written out early in the second season, but returned as a guest star in the sixth-season finale.

That role was filled by actress and comedienne Mary Louise Wilson, playing as Ginny Wroblicki, a cocktail waitress who becomes Ann's neighbor, best friend, and confidante.

[6] Wilson wrote that "aside from Lear, nobody thought I was funny...To make matters worse, each character, according to the show's formula, had to have a 'serious' moral dilemma at some point, and I was given some problem about an illegitimate child to work out in these increasingly sentimental scenes that made my bowels shrink.

Dick O'Neill and Nedra Volz made three appearances together as Orville and Emily, residents of the retirement home where the main characters put on a semiregular variety show.

She was dropped from the opening credits and not present after the fourth episode of season 9, although for a time she was still referred to as an off-screen character, while Michael Lembeck was still seen regularly as Julie's husband, Max.

Notable guest stars throughout the series run include Norman Alden, Robby Benson, Carla Borelli, Charlie Brill, Dennis Burkley, Jack Dodson, Elinor Donahue, Gwyda Donhowe, David Dukes, Greg Evigan, Conchata Ferrell, Corey Feldman, Alice Ghostley, Lee Grant, Mark Hamill, Jim Hutton, Van Johnson, Terry Kiser, Richard Kline, Christopher Knight, Jay Leno, Robert Mandan, Robert Morse, Denise Nicholas, J. Pat O'Malley, Jo Ann Pflug, Eve Plumb, Susan Richardson, William Schallert, Gretchen Corbett, Suzanne Somers, Ellen Travolta, Dick Van Patten, and Keenan Wynn.

One Day at a Time was best known in the early 1980s as a staple of the CBS Sunday-night lineup, one of the most successful in TV history, along with Archie Bunker's Place, Alice, and The Jeffersons.

The One Day at a Time Reunion was a 60-minute CBS retrospective special which aired on Tuesday February 22, 2005, at 9:00 pm ET, reuniting Bonnie Franklin, Mackenzie Phillips, Valerie Bertinelli, and Pat Harrington to reminisce about the series and their characters.

Regular cast members Richard Masur, Shelley Fabares, Nanette Fabray, Michael Lembeck and Glenn Scarpelli shared their feelings about their time on the show in separate interviews.

Accepting the award were Valerie Bertinelli, Bonnie Franklin, Pat Harrington Jr., Richard Masur, Mackenzie Phillips, and Glenn Scarpelli.

In July 2020, Bertinelli, Phillips, Lembeck and Scarpelli reunited on the Stars in the House video podcast, along with producers Norman Lear and Patricia Fass Palmer.

[15] The ensemble is led by Justina Machado, with Rita Moreno, Stephen Tobolowsky, Isabella Gomez, Marcel Ruiz, and Todd Grinnell in supporting roles.