There exists robust evidence for attitude similarity as a major cause of interpersonal liking, but previous research has ignored the case of similarity in attitudinal ambivalence or indifference. Whereas extensions of Heider’s balance theory predict that people are indifferent toward other’s ambivalence versus indifference, Byrne’s reinforcement theory of attraction predicts that people prefer interaction partners that match their own degree of ambivalence and indifference. Furthermore, Shafir’s principle of compatibility predicts preferences for ambivalent over indifferent partners in a choosing mode and the reverse in a rejecting mode. In a within-participants experiment (N = 42), the authors found that regardless of decision mode, (a) ambivalent individuals preferred ambivalent partners over indifferent ones and (b) indifferent individuals preferred indifferent partners over ambivalent ones, thus supporting reinforcement theory. The experiment provides the first evidence of interpersonal sensitivity to gradations of neutral attitudes.