Early postnatal development is a critical period for the configuration of neural networks that support emotional and socioaffective behaviors. In this sense, children raised in stressful environments are at high risk of developing maladaptive behaviors immediately or later in life, including antisocial and aggressive behaviors. However, the neurobiological bases of such phenomena remain poorly understood. Here, we showed that, in the long-term, maternal separation with early weaning (MSEW) decreased the density of somatostatin (SST) interneurons in the basolateral amygdala (BLA) of females and males, while their activity was reduced only in the medial amygdala (MeA) of males. Interestingly, this hypoactivity resulted in increased aggressivity and low social interest. To test whether the manipulation of MeASST+ interneurons was sufficient to reverse these negative behavioral outcomes, we chemogenetically expressed hM3Dq receptors in MSEW adult males. We found that the activation of MeASST+ interneurons ameliorated social interaction and reduced aggression traits. Taken together, our results highlight a role for MeASST+ neurons in the regulation of aggression and social interest and point to the loss of activity of these neurons as a plausible etiological mechanism linking early-life stress to these maladaptive behaviors later in life.