Face-to-face communication is investigated as an efficiency-enhancing mechanism in decision environments in which the appropriation activities of "outside" appropriators create coordination and monitoring problems for the communicating group. We identify three distinct problems that can threaten successful collective action. Outsiders respond strategically to reductions in appropriation by cooperating group members. Members of the communicating group deviate from agreements more frequently when monitoring is imperfect and over-appropriation can be blamed on outsiders. Groups that are allowed to communicate anticipate the potential problems and have difficulty reaching agreements or committing to a specific appropriation rule.