A typology developed from case structure and argumentation theory was used in an analysis of case types that evolved in the discussion of 12 issues during a 10-hour bargaining session between negotiators for teachers and a school board. Case types in the typology were (1) need-plan, which argues for the need to change the status quo; (2) comparative advantage, which argues that a suggested proposal will provide benefits beyond those of the current system; and (3) goals criteria, which offers a policy proposal that explicitly rejects the status quo goals or their priority. In addition, the typology contained dimensions of case fit, including agreement by both sides on the type of case presented and the way to address it, agreement to case type but not fit, and disagreement on both dimensions. Transcriptions of the negotiating sessions were analyzed by plotting the development of arguments and issues. Results indicated that comparative advantage cases emerged more frequently than did the other types of cases, and that problem solving or integrative bargaining evolved from disagreement on case type or case fit that led both sides to search for alternative proposals. Agreement on case type and case fit that remained constant throughout the sessions led to settlements derived from trade-offs. (A "flow chart" and a case analysis of one issue in the negotiating session are appended.) (FL)