Nearly 28,000 children, ranging from kindergarten to secondary-school age, commute between mainland China and Hong Kong for education on a daily basis. They are known as cross-border students (CBS)—those who legally hold permanent Hong Kong citizenship and attend schools in Hong Kong, but reside in mainland China, a unique population in the context of cross-border migration. Social media has reported various challenges faced by CBS, but systematic research on this population is limited. This study proposes a resilience and social capital framework to understand the psychosocial adjustments of CBS when faced with different levels of adversities. Using data from a cross-sectional survey of 445 CBS, this study examines how family and community social capital promote the self-esteem, mental well-being, happiness, and life satisfaction of CBS through individual resilience in the face of single and multiple adversities. The results of structural equation modelling suggest that family social capital serves as a significant promotive and protective factor for the self-esteem, mental well-being, happiness, and life satisfaction of CBS in the presence of both single and multiple adversities, while community social capital can promote only mental well-being of CBS in the presence of single or no adversity. Theoretical and practical implications of these findings for researchers, parents, and service professionals are also discussed.