This report documents work done under the International Energy Agency (IEA) Heat Pumping Technologies collaborative project IEA Annex 53, Advanced Cooling/Refrigeration Technologies Development. Research and development institutes in five Heat Pumping Technologies member countries—Germany, Italy, the People’s Republic of China, South Korea, and the United States of America—shared information on a range of advanced, lower-carbon heat pump/air-conditioning (AC) technologies. This annex was launched in response to the anticipated heavy growth in worldwide demand for AC and refrigeration by 2050. The technical scope of Annex 53 was very broad by design. It is unlikely that there will be only one or even a few so-called right solutions to the challenge. Therefore, the participants were free to investigate a wide range of possible technology solutions. Research, development, and demonstration efforts focused on advanced, higher-efficiency technology solutions for future AC and refrigeration systems. Technologies included those based on enhancements of the time-proven vapor compression cycle, electrochemical compression, absorption and adsorption (including compressor-assisted) systems, and others based on nontraditional cycles (including magnetocaloric, elastocaloric, electrocaloric, heat pipe–assisted caloric cycles, and more). Technology readiness levels for the investigated technology options ranged from approximately 2 to about 8 by the end of the annex.