A random utility model for approval voting is described, based on the nation that each voter has a personal ranking of the alternatives, with the random utilities being defined, ina standard manner, by the probability distribution on the set of all rankings. The set of alternatives chosen by a voter is made of the top alternatives in the voter's personal ranking. The size of the chosen set and the ranking are assumed to be independent. Two independent classes of necessary conditions are derived, which are used to test the model on two known sets of data. (C) 1996 Academic Press, Inc.