Fe-doped ZnS films of high optical quality were fabricated using vacuum vapor deposition. Preferential crystalline orientation and phase purity of the host ZnS films were increased by the addition of small amounts of Fe, and the spectral shape of the 2-4 μm absorption peak is maintained up to the highest concentration tested (9 at.%). However, Raman shifts of the Fe:ZnS films indicate the inclusion of disordered material at high Fe concentrations, and below-gap optical Kerr effect measurements show an increase in χ(3) correlated with this data. Nonlinear optical properties of the films were also measured using the Z-scan method at 532 nm, and saturable absorption of the Fe-based intraband levels at 2.94 μm was confirmed.