Building on research that examines the nature of similarity processes, we suggest that (i) assessments of the similarity between objects shifts systematically depending on the basis used to evaluate similarity, which is influenced by contextual factors; (ii) judgments and choices can be affected by the perceived similarity relations between items in a set; and (iii) such shifts in similarity can therefore play a key role in inferences impacting valuation and choice. In three studies, we show that changes in temporal framing (near future vs. distant future) impact evaluation and choice due to shifts in the basis of perceived similarity, leading to effects that would otherwise be unanticipated. In particular, we find that manipulating temporal context impacts evaluation and choice via its influence on which attributes form the basis of perceived similarity between choice alternatives, in addition to any direct influence it might have on preferences.