<P> For its entire run, the series was taped in Hollywood before a studio audience . Originally, it was taped at CBS Television City . Shortly after its premiere, the series began taping at Metromedia Square, where it remained until 1982 . From 1982 to 1984, the series was taped at Universal Studios Hollywood . </P> <P> 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 . Stories depicting such events as weddings, births, and other important milestones frequently stretched over two -, three -, and four - part episodes . </P> <P> The theme song for One Day at a Time, "This is It", was composed by Brill Building songwriter Jeff Barry and his wife Nancy Barry, and performed by recording artist Polly Cutter . The opening credits were originally seen over a filmed sequence showing Ann, Julie, and Barbara excitedly moving into their new home . Later, the opening credits sequence mostly consisted of clips of each cast member taken from previous episodes . </P> <P> Actors Bonnie Franklin, Pat Harrington, Jr., and Valerie Bertinelli were the only cast members to remain with the series throughout its entire run . Lead actress Mackenzie Phillips was fired after the fifth season due to growing problems with substance abuse . She later returned in a frequent recurring role . Original cast member Richard Masur was written out early in the second season but returned as a guest star in the sixth - season finale . </P>

Who wrote one day at a time theme song