Regional trade agreements are playing a greater role in shaping trade and investment rules around the world. To date the study of preferential agreements has focused on their impact on tariff preferences, but as tariffs are reduced rule-making becomes more important in trade and investment. This book addresses the role of regional and bilateral agreements in rule-making; provides an analytical framework for assessing the impact of regional and other preferential agreements on rule-making; and illustrates the role of regional agreements in a multi-level process of rule-making. Seven detailed case studies show that regional agreements can make a positive contribution to the evolution of predictable trade and investment rules, but much depends on the kind of rules they promote. To date regional rule-making has gone hand-in-hand with the evolution of multilateral rules, but recent developments give some pause for thought. It is important to understand more fully the interaction between the regional and other levels of rule-making, if the positive aspects are to be furthered and negative aspects contained.