A thermoplastic multi-layer golf ball has a core center having a diameter from about 5 mm to about 18 mm, including a first thermoplastic material having a first flexural modulus of up to about 15,000 psi, and having a specific gravity of at least about 1.5 g/cm3; a core layer outward from the core center that has a thickness of at least about 10 mm and includes a second thermoplastic material having a second flexural modulus of up to about 32,000 psi; and a cover including a third thermoplastic material having a third flexural modulus of up to about 5,000 psi. The second flexural modulus is greater than the first flexural modulus, the first flexural modulus is greater than the third flexural modulus, and the specific gravity of the core center is greater than the specific gravity of the core layer and greater than the specific gravity of the cover.