While dominated by Protestants, the nineteenth-century landed gentry of Ireland also included a minority of Catholics. Social and marriage networks of this latter group have received little scholarly attention, and this volume helps to fill that gap. It looks at the social networks for one Catholic elite family, how important religion was to that family, what the impact was on their marriage choices and the connection between their networks and education choices. With Catholicism as a common denominator for most French and Irish people during that period, the study is based on the Franco-Irish Mansfield family in Co. Kildare. It leans largely on family and estate papers and includes a quantitative analysis of a French-language diary kept by Alice Mansfield (née De Férussac) between 1877 and 1887. The diary was transcribed, translated and analysed to provide a view of the family’s social network in Ireland and France.