Lyrics for the show's theme song: This is it; this is it. / This is life, the one you get, / so go and have a ball! / This is it; this is it, / straight ahead, and rest assured, / you can't be sure at all. / So, while you're here, enjoy the view; / keep on doing what you do. / Hold on tight; we'll muddle through, / one day at a time, one day at a time! / So, up on your feet; up on your feet; / somewhere there's music playing. / Don't you worry none, / just take it like it comes, / one day at a time, one day at a time, / one day at a time, one day at a time, / one day at a time, one day at a time, / one day at a time!


When Mackenzie Phillips left the show the second time around, her character Julie was written out by first going away for training for her job and then having her leave Max and their daughter Annie. Phillips left the series due to documented substance abuse problems.


The name of the public relations firm that Ann worked for was Connors and Davenport.


Originally there were plans to spin Schneider off onto his own show after the series went off the air, but those plans never came to fruition.

After the third episode of the ninth season was filmed Bonnie Franklin decided to pull the plug of the show because the show was tired, new writers and new director in the final season and MacKenzie was back on drugs and was let go after filming the third show.

One Day At A Time was created by Whitney Blake, the mother of Meredith Baxter Birney.