In this paper, we present a series of causal maps that constitute an initial effort in the creation of a generic theory of interorganizational cross-boundary requirements analysis. Such causal structures are the result of a simulation-based study in which we explored the interactions and social processes associated with the development of trust and knowledge sharing in the development of an interorganizational information system in New York State: the Homeless Information Management System (HIMS). The paper includes the main theoretical and practical implications of the modeling and simulation work, as well as discussion of some paths to continue the exploration of collaboration in this specific context. The causal maps are organized around three themes that emerged during the modeling process. The first theme is related to trust development, and its recursive interactions with knowledge sharing and learning. The second theme is related to the importance of achieving stakeholder engagement by establishing a trusting environment as opposed to the use of authority or coercive mechanisms. The last theme is associated with the understanding of requirement definition as a social process of learning and knowledge transfer.