An interlaboratory comparison at 10 V DC has been made among 16 national, industrial, and military standards laboratories in North America. The comparison used a set of four traveling Zener dc reference standards. A pivot laboratory made measurements at the beginning, at the end, and at four other times during the comparison. The measured differences and their uncertainties are reported and used to demonstrate equivalence between each participant and the pivot, and between each participant and the National Institute of Standards and Technology (NIST). All of the differences fall within two parts in 10/sup 8/.