Finally, it is important to highlight that BA has multiple advantages that make it very efficient in terms of costs and benefits. First, it is a brief therapy, very easy to apply and disseminate (Dimidjian et al., 2011). In addition, it can be implemented by non-psychologists after appropriate training (e. g., nurses or social workers; Ekers, Richards, McMillan, Bland, & Gilbody, 2011). It can also be implemented in group format (Houghton, Curran, & Saxon, 2008; Porter, Spates, & Smitham, 2004) and in the context of primary care (Dimidjian et al., 2011). Finally, there are preliminary results that support its effectiveness in the Latino population (Bianchi & Henao, 2015; Kanter, Santiago-Rivera, Rusch, Busch, & West, 2010). Taken together, these advantages make BA of particular interest in the Latin American context, where economic limitations often do not allow for long and complex treatments, and access to trained therapists is usually limited. Therefore, the purpose of the present study is to examine the effectiveness of BA in a sample of Chilean women with chronic pain and comorbid mayor depression. For several reasons, the investigators will study the efficacy of this treatment in women with the same diagnosis of chronic pain, namely fibromyalgia. First, because this is the first RCT examining the efficacy of BA in patients with chronic pain, it is advisable to include patients with the same diagnosis to increase the homogeneity of the sample. Secondly, BA may be more effective in this type of patients, as there is a high comorbidity between fibromyalgia and depression and both disorders have been hypothesized to be manifestations of a single affective spectrum disorder (Gracely et al., 2012), Finally, preliminary results on the effects of BA in patients with pain have been reported in women with fibromyalgia.