Any chance of limiting global warming to 1.5°C—and even well below 2°C—requires a better understanding of how national oil companies (NOCs) function and what levers can be activated to support their decarbonization. Contrary to what is often perceived, not only governments but also standard setters, investors, and banks can play an important role in NOCs' decarbonization. This brief offers guidance on how such actors can drive NOCs' transition plans to align with the 1.5°C target.National oil companies (NOCs) account for half of oil and gas production, 40% of investments in the sector, and two thirds of the planet's hydrocarbon reserves. An assessment of 99 leading oil and gas companies, which includes 40 NOCs, shows that NOCs are expected to exceed international oil companies in their carbon budgets. Any chance of limiting global warming to 1.5°C and even well below 2°C therefore requires a better understanding of how NOCs function and what levers can be activated to support their decarbonization.