A multi-stage process and system for formation of a polyarylene sulfide is described. A first polymerization stage of the formation process can include reaction of a sulfide monomer with a dihaloaromatic monomer to form a prepolymer. A second polymerization stage can include further polymerization of the prepolymer with a sulfur-containing monomer and a dihaloaromatic monomer to form a low halogen content polyarylene sulfide. The amount of sulfur utilized in the second polymerization stage is a low fraction of the total amount of sulfur utilized in the multi-stage process.