Single lap bolted joints subjected to tensile load are essential joining methods in engineering design. Lateral displacement of the grip in single lap bolted joint experiment was examined and analyzed. This was different from early investigations that considered the joint fully gripped with no lateral degree of freedom. The lateral stiffness of the grip was tested to obtain the test machine properties. Tensile experiments on single lap composite-to-aluminum bolted joints were conducted, and the lateral displacement of the grip measured. Other measurements included tensile displacement, out-of-plane displacement, and surface strains. By allowing for lateral displacement, the novel finite element model predicted good results. The influence of lateral displacement of the grip was analyzed using the novel and traditional models. The novel model predicted 13 % smaller joint stiffness than traditional model. The parameters related to secondary bending were found different and the failure load of the joint was delayed because of lateral displacement of the grip.