Optical self-action in CS2and other liquids was used to make a power-limiting device having a picosecond response time. This device uses self-focusing in liquids to produce phase aberrations and laser-induced breakdown, which in turn limit the transmitted power. This device has near-unity transmission for input power below Pc, which is on the order of the critical power for self-focusing, and limits the transmitted power to a nearly constant value for input power greater than Pc. The onset of nonlinear transmission was adjusted by mixing various liquids to adjust the nonlinear refractive index. Experimental results using linearly and circularly polarized 40 ps (FWHM) pulses at 1.06 μm are presented.