Ring-type ion distributions, such as are found in the vicinity of comets, are shown to drive mirror waves unstable. Major differences are found between mirror waves driven by anisotropic bi-Maxwellian distributions and mirror waves driven by ring-type distributions; in particular, for pure ring distributions the maximum mirror wave growth rate occurs for quasiparallel wave propagation. The growth rate for ring-type driven mirror waves is approximately analytically and calculated numerically. For pure ring ion distributions, the analytic approximations are quite good. For ring-beam distributions, the mirror waves appear with a real frequency approximately equal to the ring ion Doppler frequency; the analytic approximations agree with the numerical results when the real frequency is small compared to the proton gyrofrequency so that there is little proton Landau damping. The analytic approximations provide a simple explanation for the growth dependences on propagation angle and wavelength, and leads to a simple (approximate) expression for the most unstable wavelength. Resonant instabilities can also be driven by ring-type distributions; growth rates for the nonresonant mirror wave instability are comparable to growth rates for resonant instabilities. In the presence of a ring-type distribution, the mirror waves remain nonoscillatory (&ohgr;r=0) when viewed in the frame of the newborn ions. ¿ American Geophysical Union 1989