Greg is desperate to fit in, but his efforts are constantly thwarted by Rodrick's antics. Rodrick, meanwhile, is reveling in his newfound popularity as a musician in the school's "punk" band, Löded Diper, and his schemes to embarrass Greg are ever-increasing in their audacity.
The book follows Greg's attempts to make friends, survive school dances, and avoid Rodrick's constant pranks, all while dealing with the usual teenage anxieties and mishaps. He also tries to navigate the complicated world of relationships, having a crush on a girl named Holly Hills and struggling with the social pressures of middle school.
Through it all, Greg's diary entries offer a humorous and relatable glimpse into the world of a preteen boy, showcasing the trials and tribulations of growing up, the importance of family (even when it's your annoying older brother), and the universal desire to be accepted and liked.