The interactions between individuals in a group setting are a natural areafor the application of dynamic systems modeling. Groups gathered togetherfor the purpose of generating ideas are particularly suitable for a dynamic systems approach because each individual 's rate of idea production provides a natural time-varying measure of performnce. This article presents a dynamic model (differential equations) of group idea production designed to describe the effects that group members exert on each other's rates ofprocessing. Two of the most important factors influencing group idea-generation performance, the processes of production blocking and performance matching, are explicitly included in the model. The model is related to the existing literature on the "productivity gap" observed in brainstorning groups. One version of the model explicitly includes the cognitive processes of idea generation, working memory, and output. These types of models should aid theoretical development and the assessment of the role of social and cognitive factors in both conventional and electronic brainstorming.