Russia's invasion of Ukraine and China's escalatory threats to use military force to annex Taiwan underscore the importance of resilience building in smaller nations vulnerable to expansionist powers. Despite a renewed focus among scholars and practitioners on building resilient societies, there is a gap in our current understanding of the psychological resilience a populace needs to defend and strengthen sovereignty. To help fill this gap, this article focuses on social and organizational psychology theory and research to explore (a) individual psychological motivations and (b) individual and societal capabilities that can strengthen national resilience before, during, and after a crisis (namely invasion). As a framework I use Significance Quest Theory, one of the foremost social psychological theories that synthesizes previous research on motivation. I use Mongolia, an economically and militarily smaller democratic nation bounded by authoritarian Russia and China, as a case example and incorporate quantitative survey data from Mongolians using the World Values Survey database. This paper provides a conceptual foundation of psychological resilience that future research can build upon and later integrate with other social science disciplines to further refine our understanding of how smaller nations can preserve sovereignty in the face of pressures from stronger powers.