Abstract NK cells become functionally competent to be triggered by their activation receptors through the interaction of NK cell inhibitory receptors with their cognate self-MHC ligands, an MHC-dependent educational process termed “licensing.” For example, Ly49A+ NK cells become licensed by the interaction of the Ly49A inhibitory receptor with its MHC class I ligand, H2Dd, whereas Ly49C+ NK cells are licensed by H2Kb. Structural studies indicate that the Ly49A inhibitory receptor may interact with two sites, termed site 1 and site 2, on its H2Dd ligand. Site 2 encompasses the α1/α2/α3 domains of the H2Dd H chain and β2-microglobulin (β2m) and is the functional binding site for Ly49A in effector inhibition. Ly49C functionally interacts with a similar site in H2Kb. However, it is currently unknown whether this same site is involved in Ly49A- or Ly49C-dependent licensing. In this study, we produced transgenic C57BL/6 mice expressing wild-type or site 2 mutant H2Dd molecules and studied whether Ly49A+ NK cells are licensed. We also investigated Ly49A- and Ly49C-dependent NK licensing in murine β2m-deficient mice that are transgenic for human β2m, which has species-specific amino acid substitutions in β2m. Our data from these transgenic mice indicate that site 2 on self-MHC is critical for Ly49A- and Ly49C-dependent NK cell licensing. Thus, NK cell licensing through Ly49 involves specific interactions with its MHC ligand that are similar to those involved in effector inhibition.