The network approach provides a powerful framework for analyzing psychological variables in a system, which is increasingly being applied within clinical psychology. However, the transfer of network analysis from clinical psychology to health psychology is not straightforward because of some essential differences between the phenomena under study. This paper is a response to the lack of discussion on what system of psychological variables represents and what the interrelationships between the variables mean in the recent applications of network approach to psychological variables. In addition, previous work has largely focused on node level measures thus somewhat neglecting the examination of the structural components of the overall system. In this paper, we discuss the system of psychological variables in the domains of theories on social cognition and illustrate two approaches of incorporating observable behavioral variables in a system. We illustrate these two approaches with an analysis of cross-sectional data on adolescents’ beliefs and behavior with respect to registering their choice regarding organ donation in the Netherlands. With this paper, we provide researchers with guidance on network analysis of psychological variables. Furthermore, we aim to facilitate a larger discussion on conceptualizing networks of psychological variables, which will guide the analysis and the interpretation of node level interactions as well as network level structures.