In this paper small amplitude vibrations, in the form of extensional waves, of symmetric, pre-stressed elastic laminated plates are investigated. The dispersion relation is derived for an arbitrary strain energy function in the case of a four-ply plate, each layer being composed of an incompressible, pre-stressed elastic solid. This relation is investigated both numerically and analytically for a restricted class of strain energy function. The asymptotic short wave and long wave limits are fully investigated and some asymptotic expansions obtained which give phase speed as a function of scaled wave number and pre-stress. The short wave limiting wave speed of the fundamental mode is shown to be a Rayleigh surface wave speed, a Stonely interfacial wave speed or one of two associated shear wave speeds, whilst all harmonics tend to the least of the two shear wave speeds. In the long wave limit the fundamental mode is shown to be the only one which retains finite wave speed. Stability of the laminated plate is also discussed and the paper concludes with an investigation into the behaviour of the eigenfunctions as the scaled wave number increases and the asymptotic limit of the fundamental mode is either a surface or interfacial wave speed. In such cases clear localization of stress around the surface or interface is observed as scaled wave number increases.