Carbon reduction performance is a comprehensive measure of the low-carbon development level and emission reduction effectiveness of emission entities. This book centers on two core indicators—carbon productivity and the marginal abatement cost of carbon—and constructs a systematic theoretical framework and methodological system for assessing carbon reduction performance. The book comprehensively introduces theories and methods for carbon productivity assessment that account for differences in energy and emission structures, differences in production and abatement technologies, the integration of economic and environmental comprehensive benefits, and the constraints of both market and environmental capacity. It also presents theories and methods for estimating the marginal abatement cost of carbon that address production and abatement strategy combinations, as well as data and environmental uncertainties. Furthermore, it covers methods for estimating marginal abatement cost curves of carbon in response to the dynamic nature of emission reduction targets, and approaches for identifying features of these curves based on functional data analysis, along with relevant application cases. This book provides a scientific, systematic, and operationally feasible system for the assessment, analysis, and management of carbon reduction performance. It balances academic rigor with accessibility, making it suitable for use in management and economics courses at higher education institutions, as a practical reference for researchers in fields such as energy and climate economics and carbon neutrality technology and management, and as a resource for decision-makers and managers in government and enterprises.