Early life adversity influences the diurnal cortisol rhythm, yet the relative influence of different characteristics of adversity remains unknown. In this study, we examine how developmental timing (childhood vs. adolescence), severity (major vs. minor), and domain of early life adversity relate to diurnal cortisol rhythms in late adolescence. We assessed adversity retrospectively in early adulthood in a subsample of 236 participants from a longitudinal study of a diverse community sample of suburban adolescents oversampled for high neuroticism. We used multilevel modeling to assess associations between our adversity measures and the diurnal cortisol rhythm (waking and bedtime cortisol, awakening response, slope, and average cortisol). Major childhood adversities were associated with flatter daily slope, and minor adolescent adversities were associated with greater average daily cortisol. Examining domains of childhood adversities, major neglect and sexual abuse were associated with flatter slope and lower waking cortisol, with sexual abuse also associated with higher cortisol awakening response. Major physical abuse was associated with higher waking cortisol. Among adolescent adversities domains, minor neglect, emotional abuse, and witnessing violence were associated with greater average cortisol. These results suggest severity, developmental timing, and domain of adversity influence the association of early life adversity with stress response system functioning.