This paper reanalyzes trisyllabic tone sandhi in the Tianjin dialect, which has invoked a generative line of research since mid 1980s. Among the 64 (4^3) trisyllabic tonal strings, how HL.L.L surfaces as HL.LH.L has been the crux of heated debate among the derivational and Optimality-Theo-retic approaches. This paper appeals to the notion of set consistency, the spirit of which reflects similarity-to-category in psychology and Optimal Paradigms in Optimality Theory, to account for Tianjin trisyllabic tone sandhi from a brand new perspective.