Ethnohistoric accounts and serological analyses have documented the genetic effects of transplantation and admixture of several subpopulations of Tlaxcaltecans in Saltillo, Mexico. Interpopulational affinities are assessed using skin reflectance readings taken at the upper inner arm site with a Photovolt Model 670 reflectance spectrophotometer for these groups, focusing on the barrios of La Minita and Chamizal. Genetic distance analyses based on blood groups and skin reflectance data are in close agreement and reflect differential rates of admixture for these groups. Admixture estimates for a dihybrid model (Indian-Spanish) were derived from skin reflectances and show a slight tendency for underestimation of Spanish admixture when compared to blood group estimates. Application of a trihybrid model incorporating West African admixture shows similar estimates based on blood groups, immunoglobulins, and skin color.