This paper is intended to be an overview of the current activity towards harmonisation of catalogue record exchange across the Atlantic. LIBER has had a special interest in harmonisation since it passed a resolution to explore harmonisation with the North American library community at its Annual Conference in Prague in July 1999. The paper will concentrate on current developments MARC harmonisation, because this is where most effort is currently focused, and because format harmonisation is also the logical place to start in the process. However, format change cannot be carried out in isolation, and the data carried within the formats must be harmonised as well to ensure full interoperability of record exchange.