abstract: The purpose of this phenomenological study was to explore the cultural, social, environmental, and gender factors that may influence physical activity (PA) in older Mexican American (MA) men living in Tucson, Arizona. The Mexican origin population is the fastest growing Hispanic subgroup in our nation, increasing from 20.6 million in the year 2000 to 31.8 million in 2010. Arizona has the sixth largest Hispanic population in the United States and the Mexican origin population accounts for 91% of Arizona's Hispanics. Despite the fast growing Mexican population, there are a limited number of studies that examine MAs and PA. There are even fewer interventions created to foster PA among older (≥65 years old) MA men. Fourteen individual interviews were conducted with older MA men living in Tucson, Arizona. Data was collected, organized, and analyzed according to the methodologies of Clark Moustakas and the Social Ecology Model for Health Promotion framework. Six themes emerged which reflected the older MA male's perception of health, masculinity, and physical activity: a) Retirement promotes self-care behaviors, b) Women, health care providers, and the Internet are important in promoting health, c) Aging changes physical activity, d) I take care of myself, e) Physical activity is a personal choice and lifestyle, and f) I learn and make adjustments as needed. Themes were used to create textural and structural descriptions of their experiences. Descriptions were formed into the essence of the phenomenon. The results of this study increase our understanding of health, masculinity, and physical activity in older MA men. This research will inform the development of an evidence-based PA intervention to promote cardiovascular (CV) health in older MA men that may be implemented in a variety of community-based settings. / Dissertation/Thesis / Doctoral Dissertation Nursing 2015