This article brings together a number of opinion surveys conducted in Great Britain, Northern Ireland and the Republic of Ireland in the aftermath of the signing of the Anglo-Irish Agreement at Hillsborough on 15 November 1985. In addition the fifteen by-elections of 23 January 1986 in Northern Ireland are treated as the referendum they were claimed to be by Unionists, and a brief assessment is given of the role played by the Agreement in the Irish Republic's general election of February 1987.