Off‐resonant third‐order nonlinear optical susceptibilities using degenerate four‐wave mixing measurements in solution at 1.064 &mgr;m are reported for partially doped states of the soluble, stable, reprocessible conducting polymers poly(4‐amino biphenyl) [P(4ABP)] and poly(diphenyl amine) [P(DPA)] whose synthesis and properties were reported earlier. The polymers show appreciable nonlinearities, &khgr;(3)xxxxbeing (1.4±0.3)×10−10esu for P(4ABP) and (1.3±0.3)×10−10esu for P(DPA), with a time response faster than 40 ps.