Nonlinear pulsations of main-sequence stars of 101, 10 , and l0 have been investigated by a numerical approximation technique. The pulsatinns grow to a finite limiting amplitude; the stabilizing mechanism is the dissipation of kinetic energy by shock waves. No pulsationally induced mass loss is indicated. Under the assumption that there are no other mechanisms for mass loss, the mean properties of the stars are the same as if they were stable, i.e., bright, very blue 0-type stars. For all three masses the limiting amplitudes are ( W ) 0.1, and the ratios of the maximum surface velocity to the escape velocity are also about 0.1. The qualitative result, finite-amplitude stability, is not influenced by the errors introduced by the approximation. The quantitative errors in the amplitudes are estimated to be less than a factor of 2. The lack of mass loss is a consequence of insufficiently detailed zoning. The astrophysical significance of these results and the consequences of mass loss are discussed.