The McCloskey Project uses Y-DNA testing to identify and document distinct paternal lineages associated with the McCloskey and related surname families. We also use autosomal DNA as supporting evidence. Female participants are welcome. McCloskey has an established historical association with the Ó Catháin (O'Cahan/O'Kane) a major branch of Cenél nEóghain (Cenél nEógain) in medieval Ulster. The medieval O'Cahan territory is described as "O'Cahan's Country” which surrounds the northern Derry countryside including Dungiven / Limavady / Derry / Keenaght / Roe Valley / northwestern Ulster. This project will be especially of interest to men who are either: • a surname match; or • a Y-DNA match. There are lines established in colonial America since the early 1700's that carry the Cosby and Cozby surnames and variants.