This thesis investigates the role of religion in historical economic and financial development. Attention is directed to Ireland and the Netherlands, focusing mainly on the 1861–1911 period. Both polities provide an interesting testing ground for religion-related inquiry: Ireland where a Catholic majority ceded economic power to a Protestant minority, and the Netherlands where a process of "pillarisation" divided society into distinct socioeconomic strands by religion and ideology. In the Irish case, evidence is presented that points to an economic convergence between Catholics and Protestants in the post-Famine era in what might be described as a "Catholic embourgeoisement". However, further evidence, presented at the individual level for 1911, suggests a residual human capital gap between Catholics and Protestants, even after controlling for a variety of relevant underlying socioeconomic variables. As such, while Catholics may have closed the gap with Protestants, religion still remained significant for economic variation in Ireland by the turn of the century. This temporal dimension is reemphasised in the Dutch case where Catholicism appears to have been an important catalyst for the emergence of financial cooperatives, but is less relevant for their subsequent performance.