This paper presents the results of experimental investigations on the behaviour of 1 × 2, 2 × 2, 2 × 3 model pile groups with free head condition embedded in sand under static lateral loading. The effects of spacing embedded length, size of group and relative density on load-deflection behaviour of pile group are investigated. Group interaction effects, lateral capacity of pile groups, efficiency and critical spacing are evaluated. Results indicate strong nonlinear behaviour of pile group under lateral loading. It is found that for 2 × 3 pile group with spacing to diameter (S/D) ratio of 3, the lateral load capacity is reduced by about 32%. Efficiency of closely spaced pile groups is less due to group interaction caused by the shadowing effect. The group efficiency for a pile group with three diameter spacing reduces to about 25% when the number of piles in the group increases from 2 (1 × 2 group) to 6 (2 × 3 group). The critical spacing is found to be 5D and 7D for 1 × 2 and 2 × 2 pile groups respectively.