The twelfth volume of Peanuts features a number of tennis strips and several extended sequences involving Peppermint Patty's friend Marcie (including a riotous, rarely seen sequence in which Marcie's costume-making and hairstyling skills utterly spoil a skating competition for PP), so it seems only right that this volume's introduction should be served up by Schulz's longtime friend, tennis champion Billie Jean King.

This volume also picks up on a few loose threads from the previous year, as the mysterious 'Poochie' shows up in the flesh; Linus and Lucy's new kid brother 'Rerun' makes his first appearance, is almost immediately drafted onto the baseball team (where, thanks to his tiny strike zone, he wins a game), and embarks on his first terrifying journey on the back of his mom's bike; and, in one of Peanuts' oddest recurring storylines, the schoolhouse Sally used to talk to starts talking, or at least thinking, back at her

The Complete Peanuts 1973-1974 also includes one of the all-time classic Peanuts sequences, in which Charlie Brown's baseball-oriented hallucinations finally manifest themselves in a baseball-shaped rash on his head. Forced to conceal the embarrassing discoloration with a bag worn over his head, Charlie Brown goes to camp as 'Mister Sack' and discovers that, shorn of his identity, he's suddenly well liked and successful.