The purposes of this study were (a) to evaluate the level of social adjustment of North Korean defectors, (b) to analyze the differences in social adjustment between post-traumatic stress disorder (PTSD) high-risk and low-risk groups among North Korean defectors, and (c) to determine factors, including PTSD and other related variables, that influence defectors' social adjustment in South Korea. North Korean defectors aged 18 and over were sampled using a snowball sampling method. A total of 133 cases were analyzed by hierarchical regression. Results revealed that the level of social adjustment among the defectors was rather poor, and social adjustment between the PTSD high- and low-risk groups was statistically different. The variables affecting social adjustment among the defectors included level of PTSD symptoms, self-rated economic status, job status, and gender, with PTSD symptom levels having a greater impact on social adjustment than other variables. A number of implications for the successful adjustment of North Korean defectors to South Korean society are presented.