This work tells you which Irish parish registers exist (all denominations), their starting dates, and where and how they can be located, and it links them to Griffith's Valuation of Ireland, the great survey of property holders taken between 1848 and 1864.
Here are located churches of all denominations, including Roman Catholic, and given is the earliest date of their registers. In tabular form, in alphabetical order for each of the thirty-two counties, is the name of the civil parish; the name of the Church of Ireland parish (if different), and the earliest baptism entry in the registers; the Roman Catholic parish and the earliest baptism or marriage entry in the registers; the Presbyterian congregation and its earliest baptism entries; and, if registers of dissenting churches are extant (Quaker, Methodist, Congregationalist, Baptist, etc.), it gives the beginning of their registers.
