This paper aims to inform the ongoing international climate change negotiations by examining the main arguments underlying the debate surrounding additionality of emission reductions as well as additionality of finance under the United Nations Framework Convention on Climate Change and the Kyoto Protocol. The main methods of testing additionality will also be discussed. This paper is organized in three parts. The first part summarizes the history of financial additionality, the second looks at ways to test the additionality of emission reductions. The third part concludes with proposals on how to establish clear criteria for testing additionality with the aim of reducing the controversy that surrounds the concept so as to realize its implementation in the long-term.