Argument is a critical component in policy deliberations. In this study, negotiation is viewed as a type of policy deliberation, one characterized by attack and defense of proposals, interdependence between disputants, and mixed motives of cooperation and competition. Argument in negotiation, then, functions as a reason-giving activity to enact policy. Employing a category system based on rhetorical stasis, the researchers examine whether bargainers specialize in their use of argument types and whether this specialization remains consistent throughout a teacher-school board negotiation and whether it differs for the type of settlement of agenda items. Results of the study suggest that bargainers specialize in argument types at different times during the bargaining. In the early stages of negotiation, teachers center on harm and workability arguments to prepare their case and justify the merits of their proposals, but in the latter phases of bargaining they switch to arguments on implementation to reaffirm their demands and to prioritize issues. Board members, in the early stages, rely on disadvantage, workability, and implementation arguments to establish resistance points and to refute appeals for change, but in the latter stages of negotiation they employ harm-inherency and disadvantage arguments to weigh the costs of concessions and to rationalize the settlement. This study, then, supports the existence of phase variation in bargaining and argues for a developmental approach in deciphering how negotiators who hold antithetical positions reach mutually satisfactory settlements.