Loneliness is not merely an unpleasant experience but is harmful for older adults’ health and well-being as well. While marriage buffers against loneliness in later life, even married adults experience loneliness, and aspects of adults’ marriages may either protect against or actually foster loneliness among spouses. The current study analyzed dyadic data from 1,114 opposite-sex married Irish couples who participated in the initial wave of The Irish Longitudinal Study on Ageing (2009–2011) in order to extend findings of two prior dyadic studies of marital quality and loneliness in the U.S. to older married couples in Ireland and to directly compare two theoretical and methodological frameworks used by these studies to explain associations between husbands’ and wives’ reports of marital quality and loneliness in later life. Results revealed that both spouses’ perceptions of positive and negative marital quality were significantly related with husbands’ and wives’ loneliness and that spouses’ reports of loneliness were significantly related with one another. Findings also indicated that associations between marital quality and loneliness were similar for Irish and American couples in later life. Comparison of differing modeling strategies suggested that emotional contagion may serve as a pathway for dyadic partner effects.