Insight into the characteristics and system experiences for youth who touch both the child welfare and juvenile justice systems has increased over the last decade. These youth are typically studied as one population and referred to as “crossover youth.” While this literature contributes valuable insight into who crossover youth are, studies are virtually silent on distinguishing characteristics and experiences across different pathways leading to dual system contact. This study reviews what is currently known about dual system youth generally (i.e., youth who have contact with both the juvenile justice and child welfare systems) and introduces a framework for consistently defining dual system youth and their pathways. The utility of the framework is then explored using linked administrative data for cohorts of youth aged 10 to 18 years old with a first petition to delinquency court in three sites: Cook County, Illinois between 2010 and 2014 (N = 14,170); Cuyahoga County, Ohio between 2010 and 2014 (N = 11,441); and New York City between 2013 and 2014 (N = 1272). The findings show a high prevalence of dual system contact overall, ranging from 44.8 to 70.3%, as well as wide variation in the ways in which youth touched both systems. Specifically, non-concurrent system contact is more prevalent than concurrent system contact in all sites, and individual characteristics and system experiences vary within and across these different pathway groups. Based on study findings, implications for future research on dual system youth and for developing collaborative practices and policies across the systems are discussed.