Current research suggests the importance of anxiety sensitivity (AS) in the risk for posttraumatic stress disorder (PTSD), and a growing body of research has demonstrated that difficulties in emotion regulation may also play a role. This study examined the unique relationships between AS dimensions, difficulties in emotion regulation, and a probable PTSD diagnosis among a sample of inner-city crack/cocaine dependent patients in residential substance abuse treatment. Probable PTSD participants exhibited higher levels of the AS dimension of social concerns and emotion regulation difficulties. Emotion regulation difficulties reliably distinguished probable PTSD participants from non-PTSD participants above and beyond both anxiety symptom severity and the AS dimension of social concerns. Further, social concerns did not account for unique variance when difficulties in emotion regulation was entered into the model. Results provide support for the central role of difficulties in emotion regulation relative to AS dimensions in the prediction of PTSD within a crack/cocaine dependent population.