The last episode of The Partridge Family aired on March 23, 1974. Surprisingly, the episode was called S.O.S, and they certainly needed some help at the time because the ratings practically didn’t exist. In the episode, Shirley Partridge is surprised to find out that an old boyfriend of hers is in town to make a speech.
The boyfriend was a Navy captain, but Keith and Danny Partridge thought he didn’t have good intentions towards their mother. It wasn’t written like a series finale, so viewers never found out if Keith and Danny discovered anything about the Navy captain. The writers must have been hopeful that there would be another season.