A golf ball having an inner core layer, an outer core layer essentially enclosing the inner core layer, an inner cover layer essentially enclosing the outer core layer, and an outer cover layer essentially enclosing the inner cover layer. The golf ball includes a blend of at least first and second highly neutralized acid polymers, each having a Vicat softening temperature and a specific gravity. The absolute value of the difference between the Vicat softening temperatures is no more than about 15° C. and the absolute value of the difference between the specific gravities is no more than about 0.015. Also, the method of making the blend and the golf ball is disclosed.