Tower of Power (or TOP for short) is an American R&B-based horn section and band, originating in Oakland, California, that has been performing since 1968. They are best known for their funky soul sound highlighted by a powerful horn section and precisely syncopated bass-guitar lines. There have been several lead vocalists, the most famous being Lenny Williams, who fronted the band between early 1973 and late 1974, the period of their greatest commercial success. Their biggest hits include "You're Still a Young Man", "So Very Hard to Go", "Soul With a Capital S", "Soul Vaccination", "What Is Hip?", and "Don't Change Horses (in the Middle of a Stream)".