We review several decision models to derive six fundamental requirements to collaborative spatial decision-making: perceiving changes in spatial data; retaining interpretation mindsets; externalizing actions and expectancies in spatial data; organizing divergent and convergent working modes; supporting the recognition of situation-action elements; and managing task/pattern structures. A review of the current state of the art shows limited support to some of these requirements, in particular task/pattern and divergent/convergent support. An e-planning prototype was developed to demonstrate the impact of these requirements in collaborative spatial decision-making. Results from a preliminary experiment indicate the prototype enables people to contribute, explain, exteriorize and share their ideas in relation with spatial references.