Pile-supported dolphins are designed for significant amounts of lateral loads. In this paper, the results obtained from tests carried out on model groups of piles to support dolphin-type structures are presented and discussed. Load tests have been conducted on instrumented model pile groups embedded in a marine clayey bed (liquid limit = 82% and plastic limit = 32%). The spacing between piles, number of piles in a group, and arrangement of pile group with respect to the direction of lateral loading have been varied. The results indicated that the capacity of pile group not only depends on the spacing between the piles, but also on the arrangement of piles in the group. The experimental program was further substantiated by a simplified analysis using a three-dimensional finite-element technique. The lateral group efficiencies obtained from the present investigation are compared with the published literature and found to be in good agreement. ©ASCE.