When NATO’s Information Service (NATIS) was established in 1950, campaigns in Norway to increase public support for the alliance were intensified. Domestic and foreign Government agencies, and other actors that were already active in this field, were supplemented by voluntary organisations working to promote the Atlantic cause. These organisations gradually became the main outlets for information on NATO in the country and cooperated closely with the Government, NATIS and the information services of allied countries. This article analyses the means and methods used to bolster Norwegian public support for transatlantic security cooperation, and for the political and ideological values this cooperation was based on. Norwegian attitudes to NATO were relatively positive from the outset, but expressions of neutralism and a relative lack of interest in foreign and security policies in parts of the population caused concern. Gradually, Atlanticism became the dominant position in Norwegian public opinion. The activities and campaigns analysed here were among the reasons for this. The article also argues that the scrutiny of formal and informal structures relevant for pro-Atlantic information increases our understanding of this subject and illustrates that even if information on NATO’s significance was left to each member country, NATIS had a role to play.