"leavin'" has an upbeat mood, a light, affectionate tone, soulful vocals, and sweeping string arrangements. musically, it exemplifies the group's incorporation of traditional soul styles on "sons of soul". it also features snippets of turntable scratches. it contains a sample of "if the papes come" by a tribe called quest. "billboard" observes "an overall summery feel" on "leavin'" and calls it "a smile-inducer for pop and urban outlets." gil griffin of "the washington post" writes that the "sensual" song "evokes temptations-style optimism" and that its strings and blues guitar riffs recall smokey robinson's 1967 song "i second that emotion". laura zucker of "the sacramento bee" compares saadiq's falsetto singing on "leavin'" to that of robinson.