Hello, goodbye: When do states withdraw from international organizations?

Under what conditions do states withdraw from intergovernmental organizations (IGOs)? Recent events such as Brexit, the US withdrawal from UNESCO, and US threats to withdraw from NAFTA, NATO, and the World Trade Organization have triggered widespread concern because they appear to signify a backlash against international organizations. Some observers attribute this recent surge to increasing nationalism. But does this explanation hold up as a more general explanation for IGO withdrawals across time and space? Despite many studies of why states join IGOs, we know surprisingly little about when and why states exit IGOs. We use research on IGO accession to derive potential explanations for IGO withdrawal related to domestic politics, IGO characteristics, and geo-politics. We quantitatively test these potential explanations for withdrawal using an original dataset of 493 IGOs since 1945, documenting about 200 cases of withdrawal. We find that nationalism is not the key driver of IGO withdrawals in the past. Instead, we show that geo-political factors - such as preference divergenceand contagion - are the main factors linked to IGO withdrawals, followed by democracy levels in the country and organization. These findings have important implications for research on the vitality of international organizations, compliance, and the liberal world order.