For many members of the establishment, Presbyterians were regarded as more of a threat than Catholics, especially because of their numerical superiority over Anglicans in much of Ulster. Certain restrictions were placed on Presbyterians as a result of the Penal Laws passed in the Irish parliament. Even after the passing of the Toleration Act in 1719, under which Presbyterians were granted freedom of worship, there was a strong sense of estrangement from the Anglican and landed establishment, and this was a contributory factor in the large-scale emigration of Presbyterians from Ulster to America in the eighteenth century.
In 1840, the General Assembly of the Presbyterian Church in Ireland was formed by the union of the Synod of Ulster and the Secession Synod. Today, the Presbyterian Church is the second largest Protestant denomination on the island of Ireland with over 500 congregations, overwhelmingly in Northern Ireland, but with a significant number of congregations in other parts of the island, especially counties Donegal and Monaghan as well as the city and environs of Dublin.