The neurocognitive development of moral and conventional judgments was examined. Event-related potentials were recorded while 24 adolescents (13 years) and 30 young adults (20 years) read scenarios with 1 of 3 endings: moral violations, conventional violations, or neutral acts. Participants judged whether the act was acceptable or unacceptable when a rule was assumed or removed. Across age, reaction times were faster for moral than conventional violations when a rule was assumed. Adolescents had larger N2 amplitudes than adults for moral and neutral, but not conventional, acts. N2 amplitudes were larger when a rule was removed than assumed for moral, but not conventional, violations. These findings suggest that the neurocognitive mechanisms underlying moral and conventional judgments continue to develop beyond early adolescence. (Contains 4 tables and 5 figures.)