The Open Assembly Design Environment (OpenADE) project is an initiative at the National Institute of Standards and Technology (NIST) to provide an integrated and augmented CAD environment for assembly design. The goals of the project are: (1) to identify representations and issues for the next generation of assembly-related standards and (2) assist designers with assembly considerations throughout the phases of a product’s design — from conception to final process plan development. OpenADE’s open architecture provides standard interfaces that allow it to link to commercial and non-commercial design tools: parametric design systems, virtual reality environments, assembly analysis tools, and assembly process planners. The OpenADE project has explored issues relating to knowledge representations, virtual reality, assembly-level tolerances, constraint-based specifications, and assembly process management. This article describes the OpenADE architecture and the components that have already been implemented. It also describes plans for extending OpenADE’s assembly knowledge representations and handling of geometric and kinematic constraints.