This chapter defines the subject matter and analytical scope of the study. It first describes the characteristics, formation and operation of International Environmental Agreements (IEAs) and International Labour Organization Conventions (ILOCs). It then focuses on the selection of treaties for the analysis and examines the observed patterns of treaty formation and ratification behaviour for 21 industrialised democracies. The dataset includes 83 global IEAs and 150 ILOCs adopted between 1919 and 2020. The descriptive analysis reveals not only an increase in treaties and ratifications over the last century but also a recent decline in the last two decades. Industrialised democracies show systematic differences in ratification behaviours and are generally more likely to ratify IEAs than they are to ratify ILOCs. Regional differences are evident, with northern European countries showing the highest ratification rates and non-European countries lagging behind in ratifying ILOCs. These patterns are consistent with national environmental and social policy orientations. The findings suggest that treaty ratifications are not merely symbolic but reflect deliberate choices by states that merit an explanatory analysis.