This report highlights recent initiatives to inspire policy action at a time when innovation leadership by the public and private sectors is critical to meeting the net zero challenge. Countries around the world strive to become home to the next major company emerging from a start-up with a disruptive clean energy invention, and with good reason. Whilst aiding innovation in support of climate and energy goals, nurturing innovative start-ups to maturity can also create local economic prosperity because clean energy transitions will be a major market opportunity for all countries, all century long. Already, the number of government policy measures to help start-ups get new clean energy technologies to market has risen sharply since the Paris Agreement was signed in 2015. This is extremely encouraging given that energy technology start-ups continue to face challenges attracting patient capital and governments possess some unique resources to speed them through the phases to reach technical maturity while staying in business. Based on 14 detailed case studies and in-depth interviews, this report presents a range of impressive policy measures from a variety of different country contexts, and identifies eight key insights for effective policy to support clean energy start-ups.