The use of geometric models is becoming central in the analysis and design of complex configurations, such as aerospace vehicles. Traditionally these models have been developed by a single engineer, working alone because of the way the modeling tools have been designed. While collaboration is possible via file sharing or screen sharing, none of the traditional design environments facilitate real-time collaboration. A similar problem in software development (programming) has been fixed with the introduction of pair-programming, wherein two programmers sit side by side, and work together. Pair programming has been shown to greatly improve the software development process, while only incurring a small cost penalty. Herein, the pair-programming concepts have been applied to the development of geometric models in the Engineering Sketch Pad. The efficacy of this new approach is demonstrated via two case studies.