Objective. To identify and describe new roles for medical assistants (MAs) in innovative care models that improve care while providing training and career advancement opportunities for MAs. Data Sources/Study Setting. Primary data collected at 15 case study sites; 173 key informant interviews and de-identified secondary data on staffing, wages, patient satisfaction, and health outcomes. Study Design. Researchers used snowball sampling and screening calls to identify 15 organizations using MAs in new roles. Conducted site visits from 2010 to 2012 and updated information in 2014. Data Collection/Extraction Methods. Thematic analysis explored key topics: factors driving MA role innovation, role description, training required, and wage gains. Categorized outcome data in patient and staff satisfaction, quality of care, and efficiency. Principal Findings. New MA roles included health coach, medical scribe, dual role translator, health navigator, panel manager, cross-trained flexible role, and supervisor. Implementation of new roles required extensive training. MA incentives and enhanced compensation varied by role type. Conclusions. New MA roles are part of a larger attempt to reform workflow and relieve primary care providers. Despite some evidence of success, spread has been limited. Key challenges to adoption included leadership and provider resistance to change, cost of additional MA training, and lack of reimbursement for nonbillable services. Key Words. Health care workforce, medical assistants, primary care, new models of careThe need to reform primary care delivery models has been extensively discussed in the literature, in clinical forums, and in policy arenas (Bodenheimer 2007;Gawande 2011;Fernandopulle 2013;Porter, Pabo, and Lee 2013;Bodenheimer et al. 2014a). The challenges in primary care delivery have been attributed to workforce shortages of primary care providers, an aging population with an increase in chronic conditions, reimbursement models that do not