A graph-theoretic paradigm is used to generalize the common measures of categorical clustering in free recall based on the number of observed repetitions. Two graphs are defined: Graph G, which characterizes the a priori structure of the item set defined by a researcher; and Graph R, which characterizes a subject's protocol. Two indices of clustering, denoted by T and fi, are obtained by evaluating the sum of the pair-wise products of the weights on the corresponding edges of the two graphs. The r statistic is a direct generalization of the commonly used clustering indices and reduces to the number of repetitions whenever G represents a standard categorical decomposition of a stimulus list. The fi statistic, on the other hand, extracts more information from the protocol graph, R, than does r and incorporates a distance measure based on the number of intervening items in a subject's recall sequence.