Tales of the City by Armistead Maupin - centered on a group of friends and lovers in San Francisco, quintessentially 70s
A significant portion of The Interestings by Meg Wolitzer is about a group of teenage friends in the 1970s. It does follow the teens into adulthood, though, so it isn't only set in the 70s.
A significant portion of The Interestings by Meg Wolitzer is about a group of teenage friends in the 1970s. It does follow the teens into adulthood, though, so it isn't only set in the 70s.