This study is the first to demonstrate that a self-defining period (SP) for personally relevant music emerges spontaneously in a public naturalistic setting. While previous research has demonstrated that people tend to have better memory and preference for songs from their teenage years, the theoretical relevance of these studies has been limited by their reliance on forced-choice methodology and a confinement to contemporary popular Western music. Here, we examine the record choices of famous guests ( n = 80; mean age = 61.6 years) interviewed for Desert Island Discs, a long-running popular radio programme on BBC Radio 4. Half of all choices were shown to have been most important between the ages of 10 and 30 years, and the most popular reason for their relevance was the song’s link to memories of a person, period, or place. We suggest that music is a defining feature of the SP, intrinsically connected to the developing self.