Policy network models were developed to explain differences in policy‐making and power in different policy sectors. They suggest that informal pressure group activities are more important than constitutional or institutional approaches accept. Policy communities are networks with relatively few actors, close working relations and general agreements over the scope, aims, and general institutional processes leading to policy output. Issue networks are larger, with more internal conflict and less agreement over the aims of the policy network. Policy networks may also be involved in the delivery as well as the development of policy and some argue that government's failure to understand the nature of a policy network may lead to implementation failures. Formal network theory measures the number and type of interactions between actors within a network. By examining the nature of different institutional frameworks and differences between the actors within networks formal network models may elucidate the interaction between structural and individual factors in the generation of policy outputs. Policy network models tend to be better at explaining stability, demonstrating similarities across nations or sectors where different formal institutional processes exist but poor at explaining policy change or fundamental political processes.