Replication data for: Alliance Institutionalization and Alliance Performance

Military alliances are formed with varying degrees of institutionalization. While some alliances involve little initial investment or joint planning, others involve significant peacetime costs in establishing formal structures and engaging in military coordination. Several scholars have addressed the reasons states are willing to pay these governance costs in establishing cooperation– through controlling the risks of opportunism and coordinating policy more extensively, state leaders may be able to achieve higher benefits from cooperation. What has received less systematic empirical attention, however, is the comparative performance of highly institutionalized alliances. Are alliances that represent “deeper” cooperation more reliable than their less institutionalized counterparts? The newly expanded Alliance Treaty Obligations and Provisions (ATOP) dataset includes detailed information about the institutionalization of alliances formed between 1815 and 1989. Using these data, we evaluate the effects of institutionalization on alliance performance. Surprisingly, we find no evidence that alliances with higher levels of peacetime military coordination or more formal alliances are more reliable when invoked by war. We speculate about directions for future research that might help to explain these results.