Objective: The aim of this study was to investigate whether there are different classes of body mass index (BMI) development from early adolescence to young adulthood and whether these classes are related to the number of adverse life events children experienced. Methods: Data were from the TRAILS (TRacking Adolescents' Individual Lives Survey) cohort (n = 2,218). Height and weight were objectively measured five times between participants' ages 10 to 12 years and 21 to 23 years. Parents reported on the occurrence of adverse life events in their child's life in an interview when children were 10 to 12 years old. Unconditional and conditional growth mixture modeling was used for statistical analysis. Results: “Normal weight” (75.1%), “late onset overweight” (20.1%), and “early onset overweight” classes (4.8%) were identified. In analyses unadjusted for additional covariates, children who experienced a higher number of adverse events had higher odds to be in the late onset overweight (OR [95% CI] = 1.08 [1.00-1.17]) than the normal weight class, but the association was attenuated in analyses adjusted for additional covariates (OR [95% CI] = 1.07 [0.98-1.16]). Conclusions: Three BMI trajectory classes can be distinguished from early adolescence to young adulthood. The accumulation of adverse life events is not related to BMI trajectory class.