A model is developed for ignition and laminar flame propagation in premixed gases confined in a closed chamber. Predictions follow from a numerical solution to the one-dimensional compressible Navier-Stokes Equations. The solution procedure properly accounts for multispecies diffusion, finite-rate chemical reactions, and interaction of the combustion wave with the confining geometry. A prediction of the flammability limit in ozone/oxygen is consistent with experimental data. Computations, for a mixture of 18 mole % O 3 in O 2 indicate that the confined flame (1) remains far from chemical equilibrium, (2) pulsates with significant amplitude at a slowly increasing frequency predicted by Jost's acoustic analysis, and (3) accelerates to speeds which are an order of magnitude greater than a steady state flame at the pressure levels involved.