Embracing accountability to others for one’s responsibilities within relationships is important for flourishing, yet underexamined. An interdisciplinary team defined the construct of accountability and developed an 11-item single-factor Accountability Scale. In national samples with US census demographic representation (total N = 1257), we conducted psychometric analyses using methods from classical test theory (exploratory and confirmatory factor analyses) and item response theory. The Accountability Scale demonstrated internal consistency, construct validity, test-retest reliability, and incremental validity. Accountability correlated positively with relational variables (agreeableness, empathy) responsibility-oriented variables (conscientiousness, self-regulation), virtues (gratitude, forgiveness, limitations-owning humility), relational repair, perceived meaning presence, and flourishing, inversely with symptoms (personality disorders, temper, anxiety, depression), and weakly with searching for meaning and social desirability. Accountability scores superseded demographic variables, conscientiousness, and agreeableness to predict relational repair, perceived presence of meaning in life, and flourishing. We offer the accountability construct and scale to advance human flourishing research and applied work
