Sudden gains (SGs) are rapid symptom improvements between two consecutive therapy sessions that predict treatment outcomes. This study investigated SGs in posttraumatic stress disorder (PTSD) symptoms, interpersonal relationship functioning, and social role functioning in Cognitive Processing Therapy (CPT). Participants were 121 patients and 81 therapists involved in a parent randomized controlled hybrid implementation-effectiveness trial of CPT. Descriptive analyses examined the frequency and timing of different forms of SGs. Multilevel modeling examined the impact of the three SGs on outcomes. PTSD SGs occurred more often and at different sessions than SGs in facets of social functioning. Most individuals experienced only one form of SG and there were no significant clinical or demographic differences in those who had PTSD only SGs, social functioning only SGs, or both SGs. PTSD SGs and interpersonal relationship functioning SGs both predicted changes in PTSD symptoms and interpersonal difficulties over time, but not changes in social role functioning. SGs in social role functioning predicted all three forms of outcomes. The findings suggest that there are multiple forms of SGs in CPT beyond primary symptom changes that are predictive of patient outcomes. Clinicians should highlight various SGs that patients experience to further enhance outcomes.