The purpose of this paper is to explore the authority basis of compulsory school principals in Iceland by making a general comparison to the other participating countries in the OECD Teaching and Learning International Survey (TALIS) 2018, as well as by using Hofstede's cultural dimensions theory. The study utilizes data from principals in 48 of the countries that participated in the TALIS 2018. The authority bases of the principals and of the other governing agents are explored with regard to the key task areas, which range from managerial to curriculum tasks. The authority basis of the principals and the other agents in Iceland has commonalities with most of the other Nordic countries, as well as with Baltic countries, Anglophone countries (except for Canada (Alberta)), and with many Eastern European countries. On the basis of Hofstede's cultural dimensions model, Iceland is "individualist", with a low "power distance", and it allocates more responsibility to the principals and to the other school agents at the school level than it does to the authorities. The major implication of this study for the Icelandic context is the need to enhance and strengthen the role of the school boards in terms of the professional support for principals.