The automated detection of human skin has become an important task for machine vision systems. Prior vision and graphics research on this topic has primarily focused on images acquired with conventional color cameras. Formal spectrographic analyses have largely been undertaken in the medical domain and focus on the detection of pathology. We have constructed a facility capable of producing accurate, dense and repeatable reflectance measurements. The light reflected from the skin is measured using a high resolution, high accuracy spectrograph under precisely calibrated lighting conditions. This paper presents observations from the first body of data gathered at this facility. From the measurements collected thus far, we have observed population-independent factors of skin reflectance. We show how these factors can be exploited in skin recognition. Finally, we provide a biological explanation for the existence of a distinguishing pattern in human skin reflectance.