IntroductionThe Centers for Disease Control and Prevention [CDC] used the U.S. Department of Health and Human Services' definition of mental illness as "health conditions characterized by impaired of thought, mood, or behavior (or a combination thereof) associated with distress and/or impaired functioning” (2011). Our community is exposed to large numbers of individuals with mental illnesses. Among these individuals are the widespread homeless populations. The U.S. Department of Housing and Urban Development reported that “25% of sheltered homeless individuals report serious mental illness (as cited in Allender, Rector, and Warner 2014 p. 907).” This author found the target population to be predominantly Caucasian, non-Hispanic, single males thirty-one years of age and older. By analyzing the research, this author found that multiple health disparities occur alongside mental health and homelessness. This includes heart and respiratory problems and HIV/AIDS. Without adequate health services, the homeless mental health population remains vulnerable. Summary of Available Literature After reviewing the literature, this author identified several environmental, individual, and agent factors, which make up the epidemiological triad, that contribute to the topic of mental health around the world. homeless. Environmental Factors When looking at environmental components in relation to homelessness and their mental health, this author found socioeconomic adversity, lack of health insurance and healthcare, lack of food, clothing and shelter as predominant variables. Zlotnick, Zerger, and Wolfe stated that “Limitations on staying in the hospital during the day and the competing demands of seeking food and work also in the... half of the document ......g of the 2009 patient survey. Health Service Research, 48(3), 992-1017.O'Campo, P., Kirst, M., Schaefer-McDaniel, N., Firestone, M., Scott, A., & McShane, K. (2009) . Community-based services for homeless adults with co-occurring mental and substance use disorders: A realist approach to evidence synthesis. Journal of Urban Health, 86(6), 965-985. US Department of Health and Human Services. Mental health: a report of the surgeon general. Rockville, MD: U.S. Department of Health and Human Services; Substance Abuse and Mental Health Services Administration, Center for Mental Health Services, National Institutes of Health, National Institute of Mental Health, 1999.Zlotnick, C., Zerger, S., & Wolfe, P.B. (2013 ). Health care for the homeless: What we've learned over the past 30 years and what comes next. American Journal of Public Health, 103(2), 199-205.