Social anxiety disorder (SAD) is characterized as a persistent fear of negative evaluation in social situations. This chronic condition is the fourth most common psychiatric disorder (Kessler, Berglund, Demler, Jin, & Walters, 2005), and is most often treated using cognitive behavior therapy (CBT). Although CBT has been widely demonstrated as efficacious for treating social anxiety, many individuals with social anxiety do not benefit from this treatment modality or only experience minimal improvement (Hofmann & Bogels, 2006). Therefore, clinicians and researchers have been drawn to other approaches to treatment, including mindfulness and acceptance-based interventions. Briefly, mindfulness can be described as intentional present moment awareness and a sense of nonjudgmental acceptance towards life's events (Kabat-Zinn, 1994). Mindfulness is a concept derived from eastern spiritual traditions, and has increasingly been incorporated by clinical researchers into interventions that are applied in medical and mental health settings. The acceptance component is of particular importance to the current study, and is often conceptualized along a continuum. The scope of acceptance ranges from experiential avoidance (or a lack of acceptance), where an individual is unwilling to remain in contact with internal experiences (such as thoughts and feelings), to acceptance, where an individual actively experiences his/her internal events (Hayes, Strosahl, & Wilson, 1999). Mindfulness and acceptance-based treatments, including acceptance and commitment therapy (ACT; Hayes et al., 1999), have emerged as efficacious for a wide spectrum of clinical disorders (Baer, 2003). ACT evolved from CBT and has retained some of its fundamentals, such as exposure (albeit following a different rationale), and builds upon them. Specifically, ACT aims to help clients increase acceptance of thoughts and feelings, choose valued directions for their lives, and commit to actions which are consistent with those values (Hayes et al., 1999). Within the ACT model, mindfulness and acceptance are related and distinct strategies used to increase psychological flexibility, or the ability to be aware of the present moment, in the pursuit of valued goals (Lillis, Hayes, Bunting, & Masuda, 2009). The goal of acceptance may be particularly significant for psychologists because disruptions in the acceptance component appear to be relevant in psychopathology (Hayes, Wilson, Gifford, Follette, & Stosahl, 1996). A growing body of research has provided evidence for the usefulness of mindfulness and acceptance-based interventions specifically in the context of social anxiety (Bogels, Sijbers, & Voncken, 2006; Dalrymple & Herbert, 2007; Herbert & Cardaciotto, 2005; Kocovski, Fleming, & Rector, 2009; Koszycki, Benger, Shlik, & Bradwejn, 2007; Ossman, Wilson, Storaasli, & McNeill, 2006). These findings in support of mindfulness and acceptance-based treatments for social anxiety are encouraging; however, further examinations of such interventions are necessary to build support for their use and also to address how these treatments work. Valid and reliable indices assessing mindfulness and/or acceptance are integral for understanding the mechanisms by which mindfulness and acceptance-based therapies result in beneficial changes. In recent years, a number of general self-report measures of mindfulness and acceptance have been developed and validated (Baer, Smith, & Allen, 2004; Brown & Ryan, 2003; Buchheld, Grossman, & Walach, 2001; Feldman, Hayes, Kumar, & Greeson, 2004). One such instrument is the Acceptance and Action Questionnaire (AAQ; Hayes et al., 2004). The AAQ is a measure commonly used by ACT researchers to assess experiential avoidance, or a lack of acceptance of negative private events (e.g., thoughts, feelings, physical sensations). The AAQ has been validated across a wide variety of populations and shown to be relatively psychometrically sound, and several complaint-specific measures have been adapted from this scale. …