Action is the fundamental unit of behavioral specification in models. We propose the use of Discrete EVent System Specification (the DEVS formalism) to specify the semantics of actions. Then, coupling is used to form different kinds of behavioral models. The statecharts and activities are two different approaches by which the system behavior can be described. Actions are at the core of these two approaches and therefore their specifications can collectively serve as a significant part of the overall behavior alongside with behavior of other parts such as control. Thus, we propose an approach introducing the concepts of time and state as defined in DEVS for actions; these serve as an abstraction for modeling a wide range of systems.