In 1987, Positive K signed to Nat Robinson's First Priority Music under the management of Lumumba Carson (the son of activist Sonny Carson) who would later become better known as X-Clan founding member Professor X The Overseer. With the guidance and production skills of Grand Puba of Brand Nubian and Daddy-O of Stetsasonic, Positive K released a number of songs that appeared on various underground compilations. His 1989 duet with MC Lyte "I'm Not Havin' It" was Positive K's first song to land on a Billboard music chart and it helped further establish his reputation in hip hop. Positive K soon left First Priority Music, feeling there was favoritism happening with the owner's relatives on the label.