The O'Jays were one of Philadelphia soul's most popular and long-lived outfits, rivaled only by the Spinners as soul's greatest vocal group of the '70s. In their prime, the O'Jays' recordings epitomized the Philly soul sound: smooth, rich harmonies backed by elaborate arrangements, lush strings, and a touch of contemporary funk. They worked extensively with the legendary production/songwriting team of Kenny Gamble and Leon Huff, becoming the flagship artist of the duo's Philadelphia International label. The O'Jays were equally at home singing sweet love ballads or up-tempo dance tunes, the latter of which were often mouthpieces for Gamble & Huff's social concerns. Although the O'Jays couldn't sustain their widespread popularity in the post-disco age, they continued to record steadily all the way up to the present day, modifying their production to keep up with the times.