Achieving the goals of the ParisAgreement requires countries to finance transformationalchanges with significant investments in both mitigation andresilience-building. International public climate financewith some degree of concessionality (i.e., climate finance)makes it possible to provide grants or loans with reducedinterest rates and/or longer grace or repayment periods.Given the scarcity of climate finance, this paper proposes aframework for determining the appropriate degree ofconcessionality for a program/project, and for prioritizingprograms/projects for climate action. To maximize the impactof climate finance, the degree of concessionality allocatedto a program/project should be equal to what is needed toovercome the identified barriers to implementation and makethe program/project viable. In parallel, the frameworkprioritizes programs/projects that are ambitious andtransformational. Ambitious projects contributesignificantly to achieving the objectives of the ParisAgreement. A program/project is transformational if itmeaningfully reduces barriers to implementation for futureprograms/projects that will decrease emissions or boostresilience. The paper illustrates how the three dimensions(i.e., barriers to implementation, ambitious, andtransformational) can be qualitatively assessed at fourlevels for a given mitigation or resilience-buildingprogram/project and recommends future work to operationalizethe framework into decision-making processes.