The world needs renewables, and renewables need transmission. This chapter reviews some of the key issues in transmission expansion for renewable generation, focusing on practical applications and examples from the Chilean experience. Chile has become one of the leading countries in renewable generation deployment in the region, but difficulties to plan and commission the required transmission expansion projects poses a threat to the industry’s development. Ensuring efficient and timely transmission capacity is available requires both mathematical optimization and a strong governance and institutional framework. At the system level, diverse methodologies that can be employed to develop assumptions and scenarios are summarized. An array of benefits and possible solutions that should be assessed are discussed, including flexible and non-wire solution, such as FACTS and demand response. Lastly, since the cost allocation and approval process are prone to delays and project reformulation, a more integrative approach to transmission project siting and development has become popular around the world. At the local level, transmission interconnection to the existing grid imposes significant costs on new generation projects. Coordination of multiple projects could achieve lower interconnection costs, spurring renewable integration. However, coordination has proven difficult in practical markets open to competitive generation investment. The delicate balance between central coordination and private initiative, optimality and practical feasibility, remain an issue today that practitioners and researchers alike continue to address to accelerate the transition towards the low carbon electricity grid of the future.