Families and schools are important environments that contribute to the resilience and positive development of preadolescent children. Sense of mastery, including its two central factors of optimism and self-efficacy, forms an important component of resilience during preadolescence (Prince-Embury, 2007). This study examined the interrelationships between family functioning, school connectedness, and sense of mastery in 75 children (46 girls and 29 boys) from a government school in Melbourne, Australia. Data was gathered from students aged 10 to 12 years through three self-report questionnaires. Negative perceptions of family functioning were significantly associated with the resilience factors of low sense of mastery, optimism, and self-efficacy. Higher school connectedness was significantly associated with greater sense of mastery, optimism, and self-efficacy. Additional evaluation revealed school connectedness to partially mediate the relationship between family functioning and sense of mastery. School connectedness appears to be a protective factor against the negative influence of poor family functioning. Findings highlight the important role of school connectedness in preadolescent resilience, as measured in terms of mastery, and suggest that interventions directed to enhance school connectedness are of value, particularly for children from poorly functioning families.