Cities present a unique challenge to climate governance, while they are a primary driver of climate change due to their disproportionately high levels of global energy consumption, they are also particularly vulnerable to its consequences. Recently, a trend has emerged of sustainable city initiatives that aim to develop urban climate policies on a local scale to allow the transition to a low carbon society. However, climate change transcends political and administrative borders which cannot be addressed through isolated climate policy. This suggests the need for a governance network that acts at multiple levels and integrates a variety of stakeholders as suggested by multi-level governance theory. This thesis aims to identify the optimal design of a multi-level governance system to maximize the chances for success of sustainable cities initiatives. The City of Berlin is used as a case study to examine the potential of its current climate policy framework and its aim to become a leading city in climate action. Based on interviews with experts of the policy process, this analysis determines that an optimal multi-level governance system would require effective dialogue between players at multiple levels, enhanced streamlining policy development and distributing democratic accountability with the national level as the central player.