In this study, we examined "what is mentality" in three chapters. In the first chapter, we examined the concept of mentality, in terms of its linguistic meaning and its foundational cultural dimension, followed by the scientific term used for the concept of mentality. In the second chapter, we examined mentality as a means of transformation in the historical field. We first reviewed "the history of mentalities," and secondly, we reviewed "historians of the mental." In the third chapter, we examined the relationship between mentality and philosophy, based on the notion that mentality provides the potential for critical reason and the ability to comprehend the dimensions that enable awareness to penetrate reality, or what we might call "worldview."