Guided by rejection sensitivity (RS) theory, the objective of this study was to test whether children's RS was associated with elevated negative emotional responses (less positive in-group attitudes and more negative mood) following an episode of overt peer rejection or ambiguous rejection, in comparison to acceptance. Also, the role of children's self-reported history of peer acceptance was examined. Participants were 206 children (7–11 years) who were randomly assigned to experience rejection, ambiguous rejection, or acceptance in a group simulation study. Children's group liking and negative mood depended on the 3-way interaction of experimental condition, RS and children's history. In the ambiguous condition, as expected, children with higher RS reported more negative mood, and this did not differ in low compared to high accepted children. However, RS was only associated with less positive group attitudes among high accepted children in the rejection condition, and RS was associated with more negative mood among low accepted children only (in both conditions). Findings show the relevance of RS for elevated negative mood when rejection threat is ambiguous, and the combined role of RS and social history in children's emotional responses when situations are less ambiguous.