Indium tin oxide (ITO) nanocrystals 1–10 nm in size were grown via thermal treatment of a boroaluminosilicate parent glass. The nonlinear behavior of the obtained glass-ceramic was investigated with the Z-scan technique using 550 ps pulses of a 532 nm source at a 500 Hz repetition rate. The nonlinear response was rich, with the sample exhibiting third- and fifth-order nonlinearities as well as saturable absorption and two-photon absorption (TPA), depending on the locale probed. Photoinduced changes were also observed, with high intensity exposures yielding an increased magnitude of the response when lower power trials were subsequently repeated at the same sample position. The work demonstrates that ITO nanocrystal precipitation in bulk glass yields effective nonlinear response and suggests that with further development may enable more compact devices exploiting ITO and the need for particle deposition routes.