Resilience is a complex process of adaptation to new conditions that would permit a positive outcome after adversities, traumas or other sources of stress. However, despite the growing interest in this topic, there is no universally accepted definition and no comprehensive bio-behavioural model. This systematic review aims to provide an overview of the main biological models that have been theorized to date, with a focus on new alternative theories to improve our understanding of the mechanisms underlying the development and strengthening of resilience, with potential implications for the prevention of some psychopathological disorders.This review was conducted according to PRISMA guidelines and includes 185 studies published in English in PubMed and Embase up to December 2023.Most studies use the stress-related model, which conceptualizes resilience as the absence of symptoms after the stressful event and mainly deal with the differences between stress-prone and resilient phenotypes in animals exposed to stress. However, the results of this search seem to suggest that resilience might be an independent construct with biological bases rooted in the stress system and the social brain, and widely sculptured by individual and environmental factors, especially early life events and affiliation.This work contributes to ongoing efforts to understand the intricate mechanisms of resilience, while highlighting the potential of improving social relationships since our birth to promote coping strategies towards stress and traumas, and even a peaceful world.