This essay takes the ostensibly bilingual 2009 revival of West Side Story on Broadway as a starting point to develop a synthetic history of the musical and its multiple histories, integrating not only the show’s genesis and early production history, but also the parallel histories (or “parahistories”) of revisal and critique informing the musical’s reception in the half-century since its 1957 premiere. By so tracing West Side Story’s twining histories from the musical’s earliest beginnings in 1949 through the changesupon-changes marking its 2009 revival, the essay demonstrates how compiling West Side Story’s parahistories helps to explain why one of the most canonical Broadway musicals of the twentieth century remains a source of controversy and contention in the twenty-first.