The label “resilience” has come to be used by many researchers in biology, psychology, organizational dynamics, safety, and complexity theory to describe one or another aspect of the adaptive capacity of organisms, species, groups, and organizations. As a result, there are many potential definitions of and representations for resilience, each of which suggests different ways to parameterize a system’s adaptive capacity. This chapter compares several proposed models for resilience of human systems in order to determine how they are similar and where there are substantive differences.