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 uptempo 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 have continued to record steadily all the way up to the present day, modifying their production to keep up with the times.