Exposure therapy has received a great deal of support as an effective treatment for social anxiety. However, not all those who undergo exposure therapy improve, and some of those who do respond continue to report significant levels of symptoms. A theorized mechanism of change for exposure therapy is extinction learning. Extinction learning is believed to occur across exposure sessions during which new associations are formed and stored in memory. Individuals with social anxiety are prone to engage in post event processing (PEP), or rumination, after social experiences, which may interfere with extinction learning, and thus attenuate response to treatment. The current study examined whether PEP limits treatment response to two different exposure based treatments, a group based cognitive behavioral intervention and an individually based virtual reality exposure therapy among participants (n = 75) diagnosed with social anxiety disorder. The findings suggested that PEP decreased as a result of treatment and that social anxiety symptoms for those with greater amounts of PEP improved at a slower rate of change than those with lower levels of PEP. Implications for the role of PEP on treatment response are discussed.