The capacity and competence to understand and use health information to make informed choices to make decisions is critical to maintain health. This capacity and competence, called health literacy, is affected by culture, language, trust, and the context in which the information is communicated. Improvement in health literacy involves creative solutions to translating health promotion to terms that are meaningful in the context of peoples’ lifestyles. Researchers in the public health sector are called upon to advance the science of improving health in vulnerable populations. However gaps in applying the essential concept of health literacy in population studies may impact the significance of the results. This concept analysis may assist researchers to integrate effective models of health literacy toward the development of effective health promotion studies, and ultimately, improved health states, especially in vulnerable populations.