Health literacy has become an important topic to discuss in the US healthcare system. Almost nine out of ten adults in the United States lack the knowledge and skills required to manage their health and prevent disease. While studies have shown the importance of health literacy, not may have explored its’ history and conceptual roots. Hence, the purpose of this study is to address the gap in the literature by reviewing studies related to the past, present, and the effect of health literacy. The results have shown that inadequate health literacy does affect patients’ general health and performance of the US healthcare system.