In the light of the disappointing results of the international climate change negotiations for a Post-Kyoto climate regime, some observers see the subnational state level as the big white hope providing for ambitious climate policy initiatives. Others assess subnational policies as "better than nothing". According to empirical research there is some evidence of a growing importance of the subnational state level in climate politics: It takes influence on national, supra-national and international political decision-making. It implements policies from superior political levels. Moreover it also initiates and implements independent climate mitigation goals, plans, and programs. Additionally subnational entities create (trans-)national networks thus providing for governance by diffusion. Altogether the subnational state level serves as a laboratory for experimentation in regard to climate policies and their implementation. The goal of this seminar is to study subnational state climate policy initiatives and discuss them in an international comparative perspective referring to examples from North America, Asia and Europe. We will explore and systematize policies and measures, consider their embedding in national climate policies and their interaction with superior levels. Attention will also be paid to the driving forces behind these initiatives and the actor constellations involved in the policy process.