Today, India is home to about 120 million adolescent girls, an astounding number of whom are still restrained by poor nutrition and health, lack of complete and quality education, early marriage, early and repeat pregnancies, little agency and a compromised potential. If this picture does not change drastically, India will miss out on the unique opportunity of leveraging its greatest advantage globally- its demographic dividend. This means that the country needs to act urgently, comprehensively and at scale to meaningfully include adolescent girls in its growth narrative. Needless to say, such a complex and ambitious agenda cannot be addressed alone. It needs urgent and formal collaboration between stakeholders, spanning business, government and civil society. However, bringing about such collaboration is no easy task, and agreeing to work together is no guarantee of success. Highlighting the significance of a collaborative approach to address the issues surrounding India's adolescents, this report goes a step further to share actionable insights on designing and facilitating a large-scale multistakeholder collaborative, leveraging Dasra's experience of laying the foundation for 10to19: Dasra Adolescents Collaborative, with key funders and non-profit partners. This is not a recipe book- each collaborative will have its own unique agenda and dynamics required to leverage the strengths of each stakeholder and ensure effective, collaborative action. Instead, the report outlines the building blocks that should be considered during the formative stages of a collaborative.