Contacts with the criminal legal system have consequences for a host of outcomes. Still, early life age patterns of system involvement remain to be better understood. We estimate cumulative risks of arrest, probation, and incarceration from childhood through early adulthood and assess disparities by race/ethnicity, gender, and parental education. Data come from the Transition to Adulthood Supplement of the Panel Study of Income Dynamics (n = 2,736). We use Kaplan–Meier curves and Cox regression models to estimate cumulative risks of arrest, probation, and incarceration across the early life course and document disparities by race/ethnicity, gender, and parental education, as well as at their intersections. Criminal legal system involvement is common among recent cohorts, but Black and Latinx boys and young men face especially high risks. Among Black men whose highesteducated parent completed high school or less, an estimated six in ten had been arrested, four in ten had experienced probation, and four in ten had been incarcerated by age 26. Among Latinx men whose highest-educated parent completed high school or less, an estimated four in ten had been arrested and one in four had been incarcerated by age 26. Black women also experienced high risks, with an estimated one in four arrested by age 26. We document early life patterns of criminal legal system involvement among young people who came of age during the expansion of proactive policing and mass incarceration in the United States, providing important context for understanding the role of the system in generating and exacerbating life course inequalities.