More than twenty years of case study research have produced a rich theoretical framework for understanding the outcomes that can be achieved through effective collaborative planning and the starting conditions, process characteristics, and participant attributes and behaviors that can facilitate achieving those outcomes. Multivariate modeling of collaborative development of draft long-range transportation plans by the technical advisory committees of 88 U.S. metropolitan planning organizations supports nearly all of the hypotheses that have emerged from this case study literature. In this context, however, while consensus building best practices contribute significantly to success, formal consensus-based decision making emerges as not critical.