Meeting the goals of the Paris Agreement will require an unprecedented scale of financing for low-carbon and climate-resilient development. Historically, climate finance and carbon markets have worked almost entirely independently, but this starting to shift. Blending climate finance and carbon markets would provide more flexibility, because it allows multiple international actors to provide support for the same program and to combine different financial instruments. This report funded by the Swedish Energy Agency explores both the conceptual and practical issues of “attribution” – how the emission reductions resulting from a program supported by both climate finance and carbon markets are allocated to, or recognized by, each of those financing sources. The analysis explains the importance of “proportional attribution” based on the grant-value of financing sources, and addresses questions of timing, changes in attribution over time, and links to international crediting standards. The recommendations provide important guidance for Article 6 pilot activities under the Paris Agreement.