This paper (i) formalizes conditions under which a population distribution of categorical responses to attitudinal questions (ѩtemsҩ has a scale representation; (ii) develops tests for whether a particular sample of item responses is consistent with a scale representation;(iii) develops methods for nonparametrically estimating the relation between anoutcome and a scale value; and (iv) generalizes the foregoing to the multi-scale case. Animplication of these results is that the effect of multiple latent attitudes on behaviour canbe identified, even though the attitudes of an individual can never be precisely observed.We illustrate our methods using survey data from the 1992 U.S. Presidential election, wherethe ѯutcome’ is an individual’s vote and the ѩtems’ are expressions of social and policypreferences.