<p>Vocal displays play a key role in mediating intergroup competition among primates, yet the mechanisms through which these signals influence contest outcomes remain unclear. In this study, we investigated close-range vocal encounters among six groups of black howler monkeys (<i>Alouatta pigra</i>) in Palenque National Park, Mexico. We used acoustic recordings of 58 intergroup vocal duels. We examined how structural and social features of howling bouts predict success in contests over resources. Our predictors captured three components of vocal interactions: participation (number and identity of callers), synchrony (their temporal alignment), and temporal position (which group initiated or ended the bout and which produced the longest sequence). Bayesian generalized linear mixed models revealed that specific elements of the temporal organization of vocal interactions strongly influenced the likelihood of winning. Groups were more successful when they ended the bout, when adult males terminated simultaneously, when at least one female contributed, when sequences were longer, and when the first call was a roar. Drawn encounters invariably triggered subsequent vocal duels, underscoring the role of repeated signaling in conflict resolution. These findings show that howler monkeys use coordinated and strategically structured vocal behavior as reliable indicators of motivation and cohesion, supporting assessment strategies that reduce costly physical conflicts. Our results highlight the importance of collective motivation, coordination, and persistence of contributions in shaping the dynamics of intergroup competition in primates.</p>