This study used a combination of microlevel observation data and longitudinal questionnaire data to study the relationship between differential reactivity and differential susceptibility, guided by three questions: (a) Does a subset of children exist that is both more likely to respond with increasingly negative emotions to increasingly negative emotions of mothers and with increasingly positive emotions to increasingly positive emotions of mothers ("emotional reactivity")? (b) Is emotional reactivity associated with temperament markers and rearing environment? (c) Are children who show high emotional reactivity "for better and for worse" also more susceptible to parenting predicting child behavior across a year? A total of 144 Dutch children (45.3% girls) aged four to six participated. Latent profile analyses revealed a group of average reactive children (87%) and a group that was emotionally reactive "for better and for worse" (13%). Highly reactive children scored higher on surgency and received lower levels of negative parenting. Finally, associations of negative and positive parenting with externalizing and prosocial behavior were similar (and nonsignificant) for highly reactive children and average reactive children. The findings suggest that children who are emotionally reactive "for better and for worse" within parent-child interactions are not necessarily more susceptible to parenting on a developmental time scale.