Songfacts®:

• This is the most popular song from The Brady Bunch, not counting their classic theme song, of course. The six Brady kids got into music starting with the second season of the show in 1970, when they released a Christmas album and started performing in real life. Unlike The Partridge Family or The Monkees, they weren't conceived as a music act, but by making them one, it opened up more marketing opportunities and plot lines.
  
  "It's A Sunshine Day" is part of the season 4 episode "Amateur Nite," where the kids need to come up with some cash to pay for a silver platter as an anniversary gift for their parents/step-parents, Mike and Carol. They decide to enter a TV talent show and sing the song at the audition. For the name of their group, they go with The Silver Platters.
  
  They pass the audition and sing another song on the broadcast called "Keep On." Mike and Carol see them on TV and are very impressed. In the end, as in every Brady Bunch episode, the problem is solved and all is well.
• The song was written by Stephen McCarthy, who also wrote music for various Flintstones spin-offs. The original songs featured on The Brady Bunch were generally written by songwriters who weren't household names. In some cases, royalties from these songs ended up being substantial, especially when the show went into reruns.
• The Brady Bunch ended up releasing four albums; "It's A Sunshine Day" was included on their third, The Kids From The Brady Bunch. It was also included on a 1993 compilation called It's A Sunshine Day - The Best Of The Brady Bunch.
  
  They didn't sing many songs on the show, so their albums were filled out with cover songs. On The Kids From The Brady Bunch, you can hear their renditions of "Love Me Do" and "Saturday In The Park."
• The Brady Bunch was one of many '70s shows that didn't require viewers to think very hard. The mood was upbeat and the problems always got solved. "It's A Sunshine Day" is its musical embodiment, with everybody laughing on a beautiful day.
• The actors who played the Brady kids weren't trained singers but they sounded surprisingly good. Barry Williams, who played Greg, insists they did their own singing.
  
  Their amateur aesthetic was a selling point - kids watching could imaging themselves singing like that and getting on a talent show. When the show went on the air, the theme song was performed by session singers, but starting in the second season, the kids did the vocals.