To help consider why some groups solve problems successfully but others do not, this article introduces a framework for analyzing sequences of group members' actions. The dimensions of evaluation of the previous action (supportive, critical, unresponsive), knowledge content (contribution, repetition, null), and invitational form (command, question, statement) organize twenty-seven individual actions, each with specific functions and conditions of use. Evaluations, repetitions and invitational forms link actions together to create coherent social interactions, and thereby serve as possible quantitative measures of collaboration quality. Specific individual action also helps constitute specific social interactions. Six types of social interactions that occur during group problem-solving are organized by problem knowledge distribution (no one knows a problem approach, some know, or everyone knows) and degree of cooperation (independent or cooperative). This framework's mutually exclusive categories and multi-function individual actions allow statistical analyses of many group interactions both in their entirety and infine detail. Copyright © 2000 The Executive Management Committee/Blackwell Publishers Ltd.