Having examined autonomous trade policies in Part II, I now turn to cooperation, the central focus of this book. Part III examines the conditions that make a country more or less likely to engage in cooperation than other countries or that make it more or less willing to cooperate over time. The focus is on cross-national differences between countries, building on the country-level and intertemporal analyses of Part II.

Studying cooperation requires both a definition and an operationalization of the term. This chapter provides first a definition of cooperation and then discusses the Trade Agreements Database (TAD) that I use to operationalize cooperation. Many of the decisions here reflect the fact that cooperation is a dichotomous concept, not a continuous one, and that I wish to explain both cross-national and intertemporal variation in cooperation. These theoretical issues point toward count variables for each country in the trading system.

I next define several variables derived from TAD that I use throughout the rest of the book. Foremost among these are the number of treaties that a country initiates each year and the number of treaties that each country has in effect at a given moment.