The Arsenio and Lemerise (this issue) proposal integrating social information processing (SIP) and domain theory to study children's aggression is evaluated from a domain theory perspective. Basic tenets of domain theory rendering it compatible with SIP are discussed as well as points of divergence. Focus is directed to the proposition that domains constitute latent structures of SIP. Latent structures are described as cogenerative elements of online processing rather than cumulative stores of social information. Microgenetic studies of the reciprocal role of productive systems described within SIP and latent structures attributed to domain theory are proposed as important to the study of children' aggression. Domain theory studies of social exclusion and bullying are proposed as rich contexts for future research.