The usual interpretation of the person and task variables in between-persons measurement models such as item response theory (IRT) is as attributes of persons and tasks, respectively. They can be viewed instead as ensemble descriptors of patterns of interactions among persons and situations that arise from sociocognitive complex adaptive system (CASs). This view offers insights for interpreting and using between-persons measurement models and connecting with sociocognitive research. In this article, we use data generated from an agent-based model to illustrate relations between "social" and "cognitive" features of a simple underlying CAS and the variables of an IRT model fit to resulting data. We note how the ideas connect to explanatory item response modeling and briefly comment on implications for score interpretations and uses in practice.