We do know at some point Joan did go to college, by reason of Carol her roommate in Season 1, who inevitably confesses her secret love for Joan.In terms of Joan's personal history, we do know that she has had two abortions in the past before her pregnancy with Kevin, one was practiced by a licensed physician and the other was performed by a woman who "said she was a mid-wife." ("The Good News") Joan is introduced as the head of the secretarial and steno pool, as Sterling Cooper's Office Manager.Later the same episode, Joan is watching Jackie Kennedy's Tour of the White House, while simultaneously engaging in a make-out session with Greg.("For Those Who Think Young") It however isn't until the fifth episode of the season where Joan is shown flaunting her new engagement ring in front of all the secretaries.In this episode we learn that Joan and copywriter Paul Kinsey had a relationship. In Season two, things seemed to have cooled between Joan and Roger.It isnt known how long this relationship lasted however, we do know that it didn't end well. And we are in fact introduced to Joan's boyfriend, later to become fiance; Greg Harris.
The subject of the pill is introduced when Joan sends Peggy over to her OB/GYN, Walter Emerson.
It is hinted that she may or may not have had a sexual relationship with him.
("Smoke Gets in Your Eyes") In the episode Babylon we learn that Joan has been having a lengthy affair with Roger Sterling, which we later learn has been going on since the mid 1950's.
In the third episode Joan and Greg host a dinner party for Greg's boss and colleague, it is revealed that during surgery Greg had gone wrong - Joan oblivious to the news until the dinner party is forced by Greg to sing an Americanized French version of the song C'est Magnifique on the accordion.
Managing to stay cool and collect during her rendition Joan stares disappointingly furious at Greg.