ABSTRACT In response to large numbers of senior center clients who suffer untreated depression and the dearth of geriatric mental health providers, we have partnered with senior center stakeholders to simplify Behavioral Activation (BA) to match the skill set of lay volunteers (“Do More, Feel Better”; DMFB). The lay delivery model: 1. makes use of existing volunteer resources that can address the insufficient workforce; and 2. has potential for being an acceptable and sustainable delivery model. Lay-delivered mental health interventions may be particularly well suited to overcome the language and cultural barriers faced by Spanish-speaking older adults, based on reviews of community health workers who have improved mental health outcomes for Spanish- speaking adults. However, the capacity of this model to engage the same target (increased activity) and to yield comparable clinical outcomes as professionally-delivered interventions is yet to be determined in a fully- powered trial. The parent Collaborative R01 proposes a fully powered randomized effectiveness trial testing the effect of DMFB in comparison to professionally-delivered BA (BA) on increased activity level (target) and decreased depressive symptoms. This supplement seeks to expand the existing trial for clients whose preferred language is Spanish, through translation of DMFB and enriching the RCT of DMFB vs. BA with 96 Spanish-speaking clients (32 per site). The specific aims are to: 1. Test the effectiveness of DMFB, in comparison to BA, for depressed (PHQ-9>10 and Ham-D>14) older adults (>60) on increasing overall activity level (target) and reducing depression symptoms; and 2. test whether increased activity level predicts greater reduction in depression severity and whether increased activity’s impact on depression is non-inferior across conditions. Client participants in this supplement will be a total of 96 older (>60 years) non-psychotic, non-demented individuals with elevated depressive symptoms from 2 Seattle, 2 New York City, and 2 Tampa area senior centers serving Spanish- speaking communities. Eligible clients will be randomized within senior center to either DMFB (n=48) or BA (n=48). Two lay volunteers and 2 clinicians per center will provide the intervention. Our proposal responds to the 2012 IOM report which highlighted the dearth of mental health providers for older adults and the need to develop a workforce of nontraditional providers. DMFB is a streamlined BA intervention that has high potential for sustainability by making use of an untapped volunteer resource and supervision infrastructure within senior centers. Our findings will identify effective interventions for an underserved and difficult to engage population, our partners in aging services would be pleased to implement either delivery format of BA to activate depressed older adults. Moreover, our partners have encouraged this Spanish language initiative, which has the potential to reach the large and growing ...