We demonstrate all-optical switching in an active two-dimensional photonic crystal waveguide, observing as large as $16\mathrm{nm}$ blueshifts of a leaky eigenmode at $839\mathrm{nm}$ and switching ratios of almost 70%. These results are larger than those previously observed in similar experiments performed on passive photonic crystal waveguides; the enhancement is due to resonant photogeneration of carriers by ${\mathrm{In}}_{0.12}{\mathrm{Al}}_{0.2}{\mathrm{Ga}}_{0.68}\mathrm{As}$ quantum wells in the core of the waveguide. The effective change in the refractive index of the structure is $\sim {10}^{-2}$ , with a rise time of $\sim 1\mathrm{ps}$ and a decay time of $\sim 10\mathrm{ps}$ , potentially allowing high-speed switching and fast modulation rates.