This chapter deals with the concept of being in Mesoamerican traditions, which to some extent resembles what we find in other global traditions. The chapter covers concept such as the Yucatec Maya itz and the Nahuatl teotl as a kind of basic stuff of the cosmos determining its nature. It is not quite right to call these constituents of reality, in the sense of a material such as atoms that make up the world in physicalistic systems. Instead, these concepts should be understood as expressing the nature of reality itself, that is, being itself, underlying, prior to, and sustaining all particular things.