Modeling in software engineering includes constructing static, dynamic, and behavioral representations. In describing system behavior, actions and states are two of the most commonly used concepts. In this paper, we focus on the notion of action. It generally held that the meaning of the concept of action is not that easy to grasp. According to some researchers, many existing systems do involve the notion of action, but in an obscure way. In Unified Modeling Language (UML), an action is a single atomic step within an activity, i.e., it is not further decomposed within the activity. Activity represents a behavior that is composed of actions. This paper contributes to the establishment of a broader interdisciplinary understanding of the notion of action in conceptual modeling based on a model called the thinging machine (TM). The TM uses only five primitive actions: create, process, release, transfer, and receive. The goal of such a venture is to improve the process of developing conceptual models by refining basic concepts such as action and event. To demonstrate how TM modeling represents actions, UML activity and Business Process Model and Notation (BPMN) diagrams are re-modeled in terms of the five TM actions. The results reveal the viability of the TM s five actions in modeling and relate them to other important notions such as activity, event, and behavior.