Health systems such as integrated delivery networks (IDNs) and provider networks (PNs) are becoming an increasingly influential player in the US healthcare system, driven in part by the push from volume to value. These systems have the potential to influence physician treatment behavior, and where such influence exists it offers manufacturers the ability to reach hundreds of affiliated providers at once rather than interacting with them one by one. This paper describes four aspects of IDNs and PNs that manufacturers need to understand before engaging them: