At Copenhagen in 2009, developed country Parties to the United Nations Framework Convention on Climate Change (UNFCCC) committed to a goal of mobilizing jointly $100 billion a year by 2020 from public and private sources to support climate action in developing countries. More than five years later, the sources, instruments, and channels that should count toward that goal remain ambiguous. As the Parties negotiate a new agreement for the post-2020 period, progress in meeting earlier climate finance commitments is needed to promote trust and confidence in a future climate regime. This paper contributes to the dialogue about what types of finance could count toward the $100 billion goal. Analyze this question quantitatively by projecting various finance sources forward to 2020 to demonstrate the scenarios under which reaching the $100 billion goal is possible. Analysis suggests that a combination of sources, coupled with increased public flows, will likely be needed to meet the $100 billion goal.