In the 1960s, Frankie Valli & the Four Seasons churned out hit after hit to become one of the most successful vocal groups in pop history. Their signature was Valli's stratospheric falsetto, but their success also resulted from sharp, melodic songwriting. During their prime, singles like "Sherry" and "Walk Like a Man" emphasized close-harmony singing with an urban swagger, providing the missing link between doo wop and Motown-era pop. The group topped the charts again in the '70s with an updated, disco-influenced sound. There was a resurgence of interest in the Four Seasons in the early 2000s thanks to the hugely successful Broadway musical JERSEY BOYS about the history of the beloved group.