In this work, we consider a distributed beam coordination problem, where a collection of arrays are interconnected by a certain topology. The beamformers employ an adaptive diffusion strategy to compute the beamforming weight vectors by relying solely on cooperation with their local neighbors. We analyze the mean-square-error (MSE) performance of the proposed strategy, including its transient and steady-state behavior. Simulation results support the findings that the MSE performance improves uniformly across the network relative to non-cooperative designs.