The Partridge Family, which premiered Sept. 25, 1970, was dreamed up by former Bewitched writer Bernard Slade after he saw the family singing group The Cowsills on The Tonight Show.
Screen Gems, the studio behind Bewitched, was looking for a follow-up to The Monkees, which wrapped its NBC run in 1968, and ABC was looking for a wholesome hit to pair with The Brady Bunch on Fridays.
Partridge Family, about a Northern California widow who starts a (literal) garage band with her five kids, fit the bill. Oscar winner Shirley Jones was cast as the mother; unlike the role of Carol Brady, on which she'd passed, Jones said yes to Shirley Partridge. "As much as I enjoyed The Brady Bunch, I didn't want to exclusively be the mother at home doing the.
Read more on hollywoodreporter.com