New international institutions regulating the exchange and use of materials are being established through agreements like the Nagoya Protocol, the Cartegena Protocol, and the International Treaty on Plant Genetic Resources. Although these policies respond to important stakeholder demands, they have the potential to significantly alter the ways in which individuals scientists engage in research and innovation by limiting the sharing of biological materials (Jinnah and Jungcurt, 2009; Martinez and Biber-Klemm, 2010; Atlas, 2003; De Greef 2004; Grajal, 1999; Welch et al. 2013). Within this context of contested inputs to research, this paper asks: To what extent are scientists experiencing constraints on access to biological materials? What factors explain the halting of flow of biological materials for scientific research? To what extent can blockages be attributed to national and global regulation as compared to, for example, characteristics of the material, attitudes of scientists about open exchange, collaborative structures, or intellectual property considerations? This paper first develops a framework for understanding how characteristics of the resource, regulatory constraints and scientist perceptions about the exchange environment affect an interruption in the flow of biological materials for scientific research. Framework derived hypotheses are tested using data from a unique national survey examining scientists' material exchange and use patterns for microbial, livestock, aquatic and insect germplasm. Findings show the impact of regulatory constraints, but also demonstrate how other factors such as the value of the material, expectations of non-monetary compensation, and relationships among providers and suppliers affect germplasm flows. Conclusions provide insights about the implications of new institutional controls for the future conduct of research that is reliant on biological material exchange and suggest opportunities to address current policy limitati