Early temperamental reactivity and attachment security are key predictors of children's social competence with peers. Leveraging meta-analytic evaluation of the significance of early attachment for social competence already available (Groh et al., 2014), this quantitative review examined the significance of early temperamental reactivity for social competence with peers and compared the strength of this association with that for attachment. Based on 140 independent samples (u = 382; N = 49,891), the meta-analytic association between early difficult temperament and (lower) social competence was significant (r = 0.13, z = 0.13; 95% CI [0.11, 0.16]), but decreased as time between assessments increased. Findings were similar for negative and positive emotionality. Greater negative emotionality was associated with lower social competence (r = 0.14, z = 0.14; 95% CI [0.11, 0.17], k = 93, u = 172), and greater positive emotionality was associated with better social competence (r = 0.18, z = 0.18; 95% CI [0.12, 0.24], k = 43, u = 54). Meta-analytic associations were reduced when overlapping informants and overlapping items in temperament and social competence assessments were excluded (difficult temperament: r = 0.10, z = 0.10; 95% CI [0.06, 0.13]; negative emotionality: r = 0.10, z = 0.10; 95% CI [0.05, 0.15]; positive emotionality: r = 0.10, z = 0.10; 95% CI [0.06, 0.14]). Meta-analytic associations between these broadband temperament dimensions and social competence were smaller than the meta-analytic association between attachment security and social competence. Discussion focuses on the developmental significance of early temperament for social competence and ways to reconcile literatures on early temperament and attachment in future research on the developmental antecedents of children's social competence. (PsycInfo Database Record (c) 2022 APA, all rights reserved).