The role of prior social experience in male Betta agonistic behavior was investigated in two experiments. Fish were either paired with an opponent until dominance was established naturally (Experiment II or given prior combat experience with a known aggressive or nonaggressive opponent (Experiment 2). The effects of prior social experience were then observed both in additional paired encounters and in some noncombat agonistic situations. The pairedencounter data indicate that Betta attack aggressive opponents more than nonaggressive ones and rarely attack opponents once they have submitted. In contrast to attacking, these fish do not show a significant decrease in displays once their opponent has submitted, nor do they display differentiallyto aggressive and nonaggressive opponents. The noncombatagonistic-situation data indicate that prior social experience affects both the preference of fish for viewing other conspecifics and the waning of display behaviors. These results suggest that submissive and nonaggressive behaviors can inhibit attacks but not displays by Betta, and they emphasize the necessity of controlling for prior social experience when studying aggressive behavior.