This paper studies networked control systems in the presence of communication constraints and uncertainties. We propose an ℒ1- adaption-based distributed event-triggering broadcast scheme, where ℒ1 adaptive controller is embedded in each subsystem. In this scheme, a subsystem broadcasts its state information to its neighbors when its local error exceeds a constant. We compare the resulting system with an ideal model that has perfect communication and no uncertainties. Performance bounds on these two system are derived. A trade-off is established among the performance bounds, the event thresholds, the adaptation rates, and the bandwidths of the lowpass filters in the ℒ1 adaptation structure. With this scheme, the prediction of the performance of the networked control systems in the presence of uncertainties can be significantly improved. This is important for safety-critical applications.