This article reports on a qualitative study of the construct of shared epistemic agency, investigated in the context of collaborative instructional design activities of university students. The aim of the study is to shed light on the notion of shared epistemic agency and to create empirical grounding for its theoretical description. The current study provides an account of the construct, based on a review of several theoretical conceptualizations and on the analysis of empirical material from 2 case studies from university education. We investigate shared epistemic agency within the specific framework of the knowledge creation perspective on learning, viewing it as the capacity that enables deliberate collaborative efforts of groups to create shared knowledge objects. Our study identifies and describes 2 core dimensions of shared epistemic agency: the epistemic and the regulative dimensions. We identify actions within each dimension that indicate the manifestation of shared epistemic agency in the practice of collaborative creation of shared knowledge objects. This study also distinguishes patterns of action that provide indications of how shared epistemic agency is differently articulated in the 2 groups' collaborative object-oriented activities. (Contains 6 footnotes and 7 tables.)