Why did the countries that first benefited from access to the New World – Castile and Portugal – decline relative to their followers, especially England and the Netherlands? The dominant narrative is that worse initial institutions at the time of the opening of the Atlantic trade explain the Iberian divergence. In this paper, we build a new dataset which allows for a comparison of institutional quality over time. We consider the frequency and nature of parliamentary meetings, the frequency and intensity of extraordinary taxation and coin debasement, and real interest rates together with spreads for public debt. We find no evidence that the political institutions of Portugal and Spain were worse until the English Civil War.