The socio-ecological model of communication takes a systems approach to analysis rather than a reductionist approach, meaning that it describes the complexity, interrelatedness, and wholeness of the components of a complex adaptive system rather than just one particular component in isolation from the system in which it is embedded. The two key system features of the socio-ecological model of communication and behavior change are the assumption of embeddedness, a state in which one system is nested in a hierarchy of other systems at different levels of analysis, and emergence, in which the system at each level is “greater than the sum of its parts.”