Methodological and empirical questions concerning state self-esteem are contingent upon very specific underlying commitments to “what” state self-esteem and its dynamics actually are. These are questions concerning ontology. These underlying commitments or views about “what actually exists” are not explicit, but enacted through our research actions. It is vital to bring these implicit underlying ontologies to the surface, so that we as researchers can reflect upon them, and on the assumptions that we are communicating and reinforcing with our methodological and empirical practices. In service of a conceptually solid and unambiguous framework of theoretical and methodological approaches to state self-esteem, I aim to lay bare the ontological commitments enacted in current research on state self-esteem. I show that state-self-esteem research forms two different assemblages of practices, which are repertoires of conceptual assumptions, discourse norms, methods of analysis, and operationalizations. One assemblage sketches a narrative of daily self-esteem in mechanistic terms, the other sketches a narrative of daily self-esteem in processual terms. After analyzing how concrete practices enact these ontological commitments, I reflect on how the two research assemblages might converge to benefit research on state self-esteem in the future, emphasizing the need for reflexivity from researchers.