Toddler-aged children are expected to shift from being solely dependent on parents to regulate their emotion (e.g., Fox & Calkins, 2003) to being able to independently regulate their emotions (Calkins & Johnson, 1998). Mothers' responses to children's negative emotions are expected to influence this development. Children's temperamental negative reactivity was found to moderate the effect of mothers' socialization attempts on children's regulatory behaviors, as suggested by previous theoretical and empirical work (e.g., Putnam, Sanson, & Rothbart, 2002; Rothbart & Bates, 1998). Specifically, highly negatively reactive children showed no correspondence between their mothers' attention-shifting strategies and their own attentionshifting regulation behaviors. This finding is consistent with the proposed process by which temperamentally reactive children become overaroused and unreceptive to mothers' socialization efforts (Hoffman, 1983; Scaramella & Leve, 2004). Lastly, children's reactivity did not moderate the effects of mothers' emotion-intensifying socialization on children's emotion-intensifying regulation behaviors, a finding which deserves further study.