Bereavement due to sudden loss may disrupt positive adjustment among youth, yet few studies have examined the age at which youth are most likely to first encounter sudden loss, the co-occurrence of sudden loss with other traumatic events, and the independent effects of sudden loss on academic functioning. Data were analyzed from the National Comorbidity Survey–Adolescent Supplement (N = 10,148, Mage = 15.18, 51.1% female). Youth reported on whether they had experienced sudden loss (along with 17 other traumatic events), the age at which they had first experienced sudden loss, and multiple indicators of academic functioning. Sudden loss was the most frequently occurring traumatic event among youth; approximately 30% of adolescents reported at least one sudden loss in their lifetime. Youth were most likely to have first experienced sudden loss during middle adolescence (15 to 16 years of age). Although sudden loss co-occurred with several other traumas, about 10% of youth reported experiencing only sudden loss. After accounting for demographic characteristics and other traumatic events, experiencing sudden loss was associated with lower academic achievement, lower ability to concentrate and learn, less enjoyment of school, lower school belongingness, and lower beliefs that teachers treat youth fairly. Sudden loss is common among adolescents and has important implications for school functioning. Schools may improve academic functioning by adopting routine screening for sudden loss and assessing potential need for bereavement-informed mental health services.