Ideas may impact economic policy change, but their specific effects are difficult to untangle. Material factors may influence both ideational change and policy change. In order to study these complex interrelationships, this article looks at the impact of both ideational change (the rise and fall and rise of free-market economics) and material factors (competitive pressure, crises, and domestic politics) on financial regulatory change and on one another in the United Kingdom and United States since 1846. Using a vector error correction model, I find that elite ideas influenced regulation in Britain, but not the United States. Material factors exhibited more explanatory power in both cases, although institutional differences between Britain and the United States made some shocks more or less important in either country. Material factors also influenced ideational change in both cases.