This chapter reviews the historical background on the construct of psychological trauma. It then considers recent empirical studies on individual differences in response to potentially traumatic events (PTEs). Most of the variability can be captured by four prototypical trajectories: chronic dysfunction, delayed reactions, resilience, and recovery. Major advances in theory and research on resilience to adversity came from developmental psychologists and psychiatrists during the 1970s. These pioneering researchers documented the large number of children who, despite growing up in harsh socioeconomic circumstances, nonetheless evidenced healthy developmental trajectories. Evidence for widespread resilience among survivors of the severe acute respiratory syndrome (SARS) epidemic has been reported. Resilience to trauma following disaster has been associated with male gender, older age, and greater education. Developmental theorists have for years argued that resilience to aversive childhood contexts results from a cumulative mix of person-centered variables and sociocontextual risk and protective factors.