High quality HgCdTe epitaxy is essential to the development and producibility of infrared focal plane arrays (IRFPA' s) for emerging strategic and tactical aerospace applications. The lattice mismatch between an epitaxial layer and its substrate is known to effect various layer characteristics, especially morphology and crystallinity, which impact downstream device fabrication yields. Lattice matching is thus an important issue in the continuing development of large scale HgCdTe epitaxy. This paper reviews recent progress in the development of the HgCdTe lattice matching alloys CdZnTe and CdTeSe. Improvements in growth methods, lattice parameter control, substrate size, stoichiometry control and crystallinity are presented.