The 21st International Geological Congress (IGC) was held in Copenhagen, Denmark in 1960, but was organised jointly by the five Nordic countries. It attracted 2,386 geoscientists and 948 accompanying members and was up till then the largest scientific congress held in Copenhagen. It also had more members than any previous IGC. The paper presents an overview of the practical arrangements, the lecture sessions, and the excursions, and evaluates the outcome of the Congress. The meeting took place at the threshold of the formulation of the plate-tectonic concept, which, however, was hardly discernible in the Congress Proceedings. The 430 oral presentations and 407 printed papers nevertheless supplied new information in many fields of geology, examples of which are mentioned in the present paper.