The phrase "The Summer I Turned Pretty" refers to a coming-of-age romantic drama television series and book series by Jenny Han. It centers on a girl named Isabel "Belly" Conklin, who spends summers at Cousins Beach with her family and has a long-standing crush on one of the Fisher brothers, Conrad. The story explores her experiences with first love, heartbreak, and self- discovery during the summers she spends there, especially from around her 16th birthday onward. The TV series premiered on June 17, 2022, on Amazon Prime Video, with subsequent seasons released in later years; the third and final season premiered on July 16, 2025. The original story follows Belly as she grows up, experiencing significant emotional developments each summer she visits Cousins Beach.

If more specific details about the timing or plot related to turning "pretty" are desired, it is primarily tied to Belly's 16th birthday summer when she starts to be noticed differently by the boys around her and recognizes changes in her own life and relationships.