If Fifth Dimension is The Byrds' Revolver, then the follow-up, Younger Than Yesterday, is their Sgt. Pepper. While songs like "Eight Miles High" were the band's entry point into psychedelia, YTY is a full-blown head trip. C.T.A.-102 is a tune about alien life, replete with spacy electronic effects. Backward tapes add a disorienting feel to the dreamy "Thoughts and Words" and the Eastern-influenced "Mind Gardens," and trippy lyrics abound throughout the album. But tracks like the country-rocker "Time Between" and the harmony-heavy Dylan cover "My Back Pages" keep the band in touch with their rootsy side.