Emotional security theory (EST), initially proposed as a process model for understanding relations between marital conflict and child development, has been empirically tested and validated in numerous studies over the past 20 years. This has demonstrated the relevance of children’s emotional security to consequent emotional and behavioral adjustment. Recently, investigations of EST have employed an exciting new range of multimethod processes that include biobehavioral and physiological evaluations. Together with a broadening of the ecological contexts in which EST is examined, EST research is making innovative strides in the study of process and context that promise to bring it to the forefront of social-ecological systems research.