International investment law no longer exclusively consists of self-standing investment protection treaties, but increasingly comprises preferential trade and investment agreements (PTIAs) that integrate rules on investment and trade. This book explores the impact of this new form of investment agreement on international investment relations. It asks whether PTIAs break with the rationale and objective of bilateral investment treaties or constitute their logical continuation, and whether PTIAs further fragment international trade and investment relations or create a more harmonious universe of international economic law.