This book is the first empirical account on the making of the International Solar Alliance (ISA). Announced jointly by India and France on the first day of the Paris climate talks in 2015, the ISA was conceived as a coalition of 'solar-rich' countries located between the Tropic of Cancer and the Tropic of Capricorn for optimal absorption of the sun's rays. Crucially, these 'solar-rich' countries are developing countries with poor or no energy access; witness almost three hundred sunny days in a year; have large agrarian populations; and face major gaps in the potential solar manufacturing ecosystem. In a little over two years, the ISADLled by India and backed primarily by developing countriesDLbecame a legal entity. With no perceivable competitive advantage in solar manufacturing or technologies, what explains India's relative success in bringing together countries to form this new international organization? What was the role of France in the creation of ISA? Why did India insist on a treaty structure for the new institution? Were any countries opposed to this? What are the transaction costs of bringing the 'solar rich' countries vis-`a-vis the 'solar poor' countries on board? Responding to these questions, the book draws on the political economy approach to analyse the motivations for India to steer a new treaty-based international organization. It presents the empirical evidence and arguments using three frames: process, politics, and players. Ultimately, the book illustrates a new kind of Indian economic diplomacy, making the ISA the first deliberate instrument of India's foreign policy on climate change and energy.