Following Goodman and Kruskal's interpretation of their coefficient, γA,B, a partial coefficient, γA,B|Cis defined as “how much more probable it is to get like than unlike orders in measuresAandBwhen pairs of individuals differing onAand onBand tied onCbut unselected on any other measure are chosen at random from the population.” It is shown that this coefficient is a weighted sum of the values of γ in the various strata defined by categories ofC, where the weight in stratumiis its proportion of the total pairs which differ onAandBand are tied onC.An empirical example illustrates the calculation of the co-efficient.