Canada has a more restrictive biotechnology policy than the United States. Adopting a similar-cases-research-design, this article shows that policy networks explain this difference. The overlapping nature and the boundary between the multiple networks relevant to biotechnology in each country are distinct. In the United States, two policy networks deal with biotechnology. One primarily handles agricultural plants, while the other deals with food; key state actors overlap. In contrast, networks in Canada are separated between those dealing with regulation with two overlapping networks assessing environmental and health risks, and a network to manage biotechnology promotion. Promotion and regulation thus constitute a network boundary in Canada, but not in the United States, where networks deal with these two issues simultaneously. American networks have promoted beliefs favourable to more permissive regulatory preferences than the Canadian environmental and health risk assessment networks and American biotechnology policies are therefore even more permissive than those of Canada.