Background: Psychological immunity comprises an individual__ampersandsignrsquo;s ability to safeguard and promote mental health. Ol__ampersandsignaacute;h__ampersandsignrsquo;s psychological immune system is a multi-dimensional model which incorporates factors affecting mental health like optimism, selfesteem, and control over emotional faculties; it consists of personal protective and promotive resources that offer immunity to environmental stress. This model can be useful for exploring relevant psychological phenomena like resilience and the cognitive and behavioural concepts associated with it. Objective: To describe psychological immunity and the key concepts driving it. Method: Narrative review of literature relevant to psychological immunity. Conclusion: It has been pointed out that the factors influencing resilience have useful equivalents within the psychological immune system model, implying that resilience is a key factor promoting psychological immunity. The psychological immune system model will be important for investigating interactions with the biological immune system, especially concerning interventions that can enhance health, like resilience training. Furthermore, the model can act as a unifying framework for psychological phenomena like well-being and coping.