This study examined a new prewriting tool, argumentation vee diagrams (AVDs), which are used to write reflective opinion essays. AVDs are based on the theoretical concept of argument-counterargument integration, which involves evaluating and integrating both sides of an issue before developing a final conclusion on a controversial question. In a test of the effectiveness of AVDs, 45 undergraduates at a large, southwestern university were randomly assigned to an experimental or control group. Both groups wrote 4 opinion essays over a 4-week period. The experimental group also received training on using the AVDs, including instruction on criteria for weighing arguments. Results indicated that AVD training was effective in enhancing argument-counterargument integration. Furthermore, examination of integration strategies used by participants revealed a new strategy, "minimization," which was not previously part of E. M. Nussbaum and G. Schraw's (2007) argument-counterargument integration framework. Minimization involves curtailing the importance or extensiveness of a problem or advantage as a heuristic shortcut for weighing advantages and disadvantages. The role of critical questions and argumentation schemata in argument-counterargument integration is discussed. (Contains 3 figures and 6 tables.)