O Sister! is a tribute to the North American popular music from the 1920s and 30s, and in particular, to the golden ages of “Dixie” and “Swing”. The Boswell Sisters, the band’s main artistic influence, were a ground-breaking female vocal jazz trio perhaps not as popular as they deserved to be, in spite of being imitated and admired by many later vocal jazz groups. The big care to staging, dressing and choreographies give to the band an enormous live impact.