This article uses experimental data to test for a complementary relationship
between formal regulations imposed on a community to conserve a local natural
resource and nonbinding verbal agreements to do the same. Our experiments were
conducted in the field in three regions of Colombia. Our results suggest that the
hypothesis of a complementary relationship between communication and external
regulation is supported for some combinations of regions and regulations but
cannot be supported in general. We conclude that the determination of whether
formal regulations and informal communication are complementary must be made
on a community-by-community basis. (JEL C93, H41, Q20, Q28)