This paper presents an experimental study of the contact stress distribution beneath two interfering rigid strip foundations resting in frictionless contact with a layer of dense sand underlain by a smooth rigid base. It is found that the interference between the two foundations has a significant influence on the contact stress distribution. In the absence of interference, the contact stress distribution beneath a single foundation exhibits a symmetrical shape. As the spacing between the foundations diminishes the contact stress distribution exhibits an asymmetrical shape. Keywords: contact stresses, foundation interference, plane strain tests, experimental studies.