This paper investigates how aspects of policy networks facilitate or inhibit the efforts of public bureaucracies to adopt and implement science policy innovations. Three correlated dimensions of policy networks – permeability, size, and tie strength – strongly influence adoption and implementation outcomes. Policy networks tend to expand and contract cyclically along these network dimensions.

Policy adoption and implementation are not binary variables, but rather continually occurring processes that also cycle. Successful adoption and implementation outcomes are most likely when adoption-implementation and network expansion-contraction cycles are aligned such that adoption occurs when the policy network is more permeable, larger, and more laden with weaker ties, and implementation occurs when the network is less permeable, smaller, and more laden with stronger ties. When cycles are not optimally aligned, adoption and implementation efforts are more likely to fail or stall.

These arguments draw on literature concerning policy networks as well as collective action and social capital. They are illustrated with case sketches that describe the attempts by environmental bureaucrats in six U.S. Mid-Atlantic states to adopt and implement a type of science policy innovation for wetland management. The sketches draw upon more than 90 interviews with environmental bureaucrats and stakeholders in the region, as well as secondary-source analysis and survey research.