In a successful transition from youth to adulthood, individuals pass through a sequence of roles involving school, work, and family formation that culminate in their becoming self-sufficient adults. However, some “disconnected” youth spend extended periods of time outside of any role that constitutes an element of the pathway towards adult independence. Assisting these youth requires a systematic understanding of what “disconnection” means, how many disconnected youth there are, who these youth are, and how the scale of the problem has evolved over time. Using the National Longitudinal Surveys of Youth for 1997 and 1979, we address these issues by creating concrete definitions of “disconnection spells” using rich data on youths’ enrollment, work, and personal histories. We estimate a multi-state duration model to account for right censoring and to understand differences across salient sub-groups. Our estimates imply that in the early 2000s, almost 19% and 25% of young men and young women, respectively, experienced a disconnection spell by age 23 using our basic definition. These rates are substantially higher for certain sub-groups defined by race/ethnicity, parental education, and government aid receipt, rising as high as 30+% by age 23. Approximately 60% of youth with a disconnection spell have it last longer than a year, and close to 10% have it last longer than 4 years. However, once reconnected, a majority of youth go at least three years without a re-disconnection spell. Patterns of initial disconnection changed markedly from the 1980s to the 2000s, as young women saw a 12 percentage point decline over time. Moreover, the Black-White gap in disconnection has fallen for women, but increased for men. Our profile of disconnection experiences provides a starting point for government agencies aiming to understand where, how, and with whom to intervene to prevent lengthy disconnection spells.