This essay provides a critical review of two recent books by Friedrich Kratochwil and Poul Kjaer respectively regarding the status of law and constitutionalism in world society. The one (Kratochwil) writes from within and against the discipline of international relations “as his prism.” The other (Kjaer) writes from within and against a school of sociology of law spanning from Niklas Luhmann to its reconstruction in the work of Gunther Teubner. Both works grapple with the place and role of law in international relations and social ordering in the context of globalization and economic and social crises today. Their books should be viewed as necessary complements to understanding the prospects and limits of transnational legal ordering through international law and functionally differentiated transnational organizations. Today, transnational legal orders extend beyond the domain of nation-states and the society of nation-states and engage with the transnational functional differentiation of society theorized by Kjaer. They involve, ultimately, the study of praxis, emphasized by Kratochwil, including the interaction between transnational, national, and local legal practice. The work of Kratochwil and his emphasis on praxis and that of Kjaer and his focus on functionally differentiated transnational legal orders provide critical components for such analysis. They complement each other in enhancing our understanding of international and transnational legal ordering today in response to ever-new and ongoing global and transnational problems and crises.