Campbell recorded prolifically throughout the 1960s; notable early ska releases include: "Madness" (1963), "Wash Wash" (1963, with Ernest Ranglin on bass), "One Step Beyond" (1964) and "Al Capone" (1964). The documentary "This is Ska" (1964), hosted by Tony Verity and filmed at the Sombrero Club, includes Campbell performing his Jamaican hit "Wash Wash". In 1964 Campbell met World Heavyweight Champion boxer Muhammad Ali who invited him to attend a Nation of Islam talk at Mosque 29 in Miami. That year Campbell joined the Nation of Islam and also started to release material, including a version of Louis X's "White Man's Heaven is a Black Man's Hell," on his own imprint label called "Islam". In 1965 he appeared in "Millie in Jamaica" (a film short about Millie Small's return to Jamaica after the world-wide success of "My Boy Lollipop") which was broadcast on Rediffusion's Friday evening pop show "Ready, Steady, Go!" Campbell had a top twenty hit in the UK with the single "Al Capone" (no. 18, February 1967).