New directions of design for mathematics education may require insights from multiple resources including different theoretical perspectives. Rather than as a problem, the Networking of Theories conceptualizes this diversity as having potential for teaching and learning. Over the past decade more insight has been gained into how theories may work together and what this may offer. This paper provides an overview on research in which the Networking of Theories is used as a research practice including the notion of theory. By examples it highlights networking strategies and methodologies as ways to link theoretical perspectives and their potentials systematically. Reflecting on a recent design study that includes technology as part of a multimodal perspective, a case of networking theories across disciplinary boundaries to integrate technological as well as educational design is also considered as part of interdisciplinary design research.