Polymers that have one of the three complementary colors (red, green, and blue, RGB) in the neutral state and high transmissivity in the oxidized state are the key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers have been reported up to date, green polymers with highly transmissive oxidized states, high optical contrasts, fast switching times, and advanced long-term switching stabilities were essentially missing in the literature. This paper reviews our previous efforts towards realization of neutral state green polymers with highly transmissive oxidized state. The key to this problem was found to be the synthesis of donor-acceptor polymers bearing benzothiadiazole or quinoxaline derivatives as the acceptor and electron rich 3,4-ethylenedioxythiophene unit as the donor component. Green neutral state polymeric materials with highly transmissive oxidized state with excellent electrochromic properties have been realized with the design and synthesis of these types of materials. A solution processable green polymeric material has also been realized via chemical polymerization that has shown all superior properties of the electrochemically synthesized counterparts.