Both negative posttraumatic cognitions and posttraumatic stress disorder (PTSD) symptoms decrease over the course of cognitive-behavior therapy for PTSD; however, further research is needed to determine whether cognitive change precedes and predicts symptom change. The present study examined whether weekly changes in blame predicted subsequent changes in PTSD symptoms over the course of cognitive processing therapy (CPT). Participants consisted of 321 active duty U.S. Army soldiers with PTSD who received CPT in one of two clinical trials. Symptoms of PTSD and blame were assessed at baseline and weekly throughout treatment. Bivariate latent difference score modeling was used to examine temporal sequential dependencies between the constructs. Results indicated that changes in self-blame and PTSD symptoms were dynamically linked: When examining cross-construct predictors, changes in PTSD symptoms were predicted by prior changes in self-blame, but changes in self-blame were also predicted by both prior levels of and prior changes in PTSD. Changes in other-blame were predicted by prior levels of PTSD, but changes in other-blame did not predict changes in PTSD symptoms. Findings highlight the dynamic relationship between self-blame and PTSD symptoms during treatment in this active military sample.