A previously described starlike copolymer consisting of a lignin derivative (hydroxypropyl lignin) and caprolactone has been blended with poly(vinyl chloride) (PVC) over a composition range of 0-100%. Solvent-cast films of the blends were examined with regard to thermal, mechanical, crystallinity, and morphological characteristics. In addition, the blends were examined with regard to aging effects. The results suggest that the lignin/caprolactone copolymer forms either a miscible (by thermal analysis) or a nearly miscible (with phase dimensions in the order of 10-30 nm) system in which physical properties are modified over a wide range of modulus and elongation. Blends with copolymer content exceeding 50% reveal partial caprolactone crystallinity that increases with age. Lignin derivative not copolymerized with caprolactone, by contrast, produces macrophase-separated structures with exceedingly poor properties. Lignin caprolactone starlike copolymers are materials ideally suited as plasticizers for PVC.