Using data from a stratified random sample of 281 foreign-born adolescents and their parents in the United States, this study provides data on migration-related trauma exposures and examines how the migration process influences the risk of experiencing trauma and developing posttraumatic stress disorder (PTSD). We find that 29 percent of foreign-born adolescents and 34 percent of foreign-born parents experienced trauma during the migration process. Among those that experienced trauma, 9 percent of adolescents and 21 percent of their parents were at risk for PTSD. Pre-migration poverty combined with clandestine entry into the U.S. increased the risk of trauma and the subsequent development of PTSD symptoms. Post-migration experiences of discrimination and neighborhood disorder further exacerbated this risk, while social support and familism mitigated it. Our results emphasize the importance of understanding how factors prior to, during, and after migration combine to influence the health of immigrants.