--- - |2 Abstract The present research examined children’s anger proneness, emotion understanding, and maternal sensitivity during toddlerhood as predictors of children’s hostile attribution bias (HAB) during the later preschool years. At 2.8 years (N = 128), maternal sensitivity (e.g., child‐centered behavior) was observed during mother–child play and snack, and parents reported on children’s anger proneness. At 3.3 years, emotion understanding (i.e., ability to identify emotional expressions accurately) was measured via an interactive puppet interview. At 4.8 and 5.4 years, children's HAB was assessed via child responses to hypothetical vignettes of ambiguous peer provocations. Path models revealed that maternal sensitivity predicted fewer hostile attributions. In addition, emotion understanding and maternal sensitivity emerged as buffers against the negative effect of anger proneness on HAB. Specifically, greater anger proneness was associated with more frequent hostile attributions, but only when children had lower emotion understanding or had mothers who were less sensitive. The findings highlight the interplay between intrapersonal and interpersonal factors in early childhood that contribute to a hostile attribution bias during the preschool period. - Social Development, EarlyView.