Criteria for design of a wave barrier to protect the proposed Honolulu International Airport Reef Runway from breaking waves were developed in wave flume model tests Structures with tribar and quarrystone armor units placed in single and multiple layers, on homogeneous and composite slopes, were subjected to both overtopping and non-overtopping breaking waves Data on wave runup, armor unit stability, quantities of overtopping water, and transmitted wave heights were obtained using a 1 50 bottom slope, which modeled the irregular coral bathymetry seaward of the proposed structure The model to prototype scale ratios ranged from 1 5 to 1 35 Model Tests indicated that the weight of armor units placed below one-third the water depth may be three-fourths that of the units located near the water surface It was noted that the maximum wave runup was 1 8 times the water depth fronting the structure Data were obtained concerning quantities of overtopping water and transmitted wave heights over the low barriers The study augments available criteria for economical design of structures subjected to breaking waves.