The Critical Mass Initiative was created in early 2010 to catalyse public-private collaborations to help pioneer a new wave of bankable and scalable transactions in low-carbon infrastructure, in developing and emerging economies. This is an unique platform convened by the World Economic Forum, International Finance Corporation and United Nations Foundation, in association with the Institutional Investors Group on Climate Change and the Investor Network on Climate Risk. PwC was the Project Adviser to the World Economic Forum for this initiative. The Critical Mass Initiative adopted a distinctive co-design and learn-by-doing approach to help participants innovate in their approach toward designing investment transactions in low-carbon infrastructure in developing countries. It did this by hosting three different public-private investment laboratories at the project,program and sector level. These included India Solar (on a projects level), the South African Renewables Initiative (on a programmatic level) and Energy Efficiency (on a sector level).The work shows that, at this stage of the market building process for low carbon infrastructure investments in developing and emerging economies, there can be significant value in creating hubs and platforms to host collaborations among public and private sectors, bilateral and multilateral development banks. From these public-private platforms, the first wave of iconic projects and pioneering policy innovations can emerge.All the key actors who must be involved in the agenda can build experience, capacity and relationships from engaging in these kinds of activities.We trust that these findings will provide useful guidance to various stakeholders in the public and private sector to help shape broader and deeper investment innovation programmes during 2011.