The present invention is directed to a method of forming a golf ball that contains an interpenetrating polymer network, or IPN, which includes at least two polymeric systems, in one or more of the layers. The first polymeric system may include a polyurethane-based or polyurea-based system having blocked isocyanate groups and the second polymeric system may include an epoxy-based or acrylic-based system, wherein the two systems are polymerized or cured simultaneously or sequentially to form an IPN.