Developmental psychologists have long argued that the capacity to distinguish moral and conventional transgressions develops across cultures and emerges early in life. Children reliably treat moral transgressions as more wrong, more punishable, independent of structures of authority, and universally applicable. However, previous studies have not yet examined the role of these features in mature moral cognition. Using a battery of adult-appropriate cases (including vehicular and sexual assault, reckless behavior, and violations of etiquette and social contracts) we demonstrate that these features also distinguish moral from conventional transgressions in mature moral cognition. Each hypothesized moral transgressions was treated as strongly and clearly immoral. However, our data suggest that although the majority of hypothesized conventional transgressions also form an obvious cluster, social conventions seem to lie along a continuum that stretches from mere matters of personal preference (e.g., getting tattoos or wearing black shoes with a brown belt) to transgressions that are treated as matters for legitimate social sanction (e.g., violating traffic laws or not paying your taxes). We use these findings to discuss issues of universality, domain-specificity, and the importance of using a wellstudied set of moral scenarios to examine clinical populations and the underlying neural architecture of moral cognition.