We document racial and ethnic disparities in the propensity of law enforcement to formally book juvenile arrests. A fair share of these disparities can be attributed to differences in arrest offense severity and arrest history as well as cross-agency differences in practice. The disparities are the largest for age ranges and offenses where the greatest discretion is exercised. We explore whether booked arrests increase the likelihood of future arrests and bookings exploiting the discontinuity in the booking probability at age 18. The results suggest sizable effects of a prior booking on the likelihood of a future arrest and subsequent booking.