A violation of procedure invariance in preference measurement is that the predominant or prominent attribute looms larger in choice than in a match ing task. In Experiment 1, this so-called prominence effect was demonstrated for choices between pairs of options, choices to accept single options, and preference ratings of single options. That is, in all these response modes the prominent attribute loomed larger than in matching. The results were replicated in Experiment 2, in which subjects chose between or rated their preference for pairs of options which were matched to be equally attractive either in the same session or 1 week earlier. On the basis of these and previous results, it is argued that the prominence effect is a reliable pheno menon. However, none of several cognitive explanations which have been offered appears to be completely viable.