Decisions made at the early stages of design are critical in relation to the later stages of the building design and construction process. This is becoming more evident as the design process and a variety of building techniques/materials become more complex. Computers are currently ubiquitous in later stages while absent in the earlier design stages which are still dominated by manual techniques. One of the consequences of the situation is the need to translate manual design solutions into a format that can be used by computers at the later stages, thus increasing the probability for errors and incompatibilities. This research project provides a clear description of the early building design process in a way that makes it possible to formulate basic requirements for successfully supporting the process. These basic requirements are then used to compare with existing computer tools in order to determine what is the current available support. An in-depth study, using the technique of protocol analysis, of eight designers during early building design sessions is carried out in order to identify the features that are needed in a computer environment. Specifications are defined based on this study to guide the creation of a system to support the early building design process using computers. The research project formulates concepts for computer-supported early building design and uses these to create a prototype that satisfies a subset of the specifications. This prototype is described and then tested in a way that favorably compares it to a manual design session showing superiority in design management and interpretation of ideas while reducing efforts.