Wireless is the dominant mode of personal communication, but by nature, it is vulnerable to interference from various sources. The increasing density of radios, coupled with the growing number of different protocols, dictates that future wireless devices will require the ability to coexist and operate in a crowded and often unregulated electromagnetic environment. I will present a set of architectures and mechanisms for wireless coexistence. These mechanisms are intended as general primitives, enabling future wireless networks to be architected such that they are aware of who thir RF neighbors are, what they are doing, and how to respond to them. I will be focusing on two systems, each demonstrating how changes at different levels across the network stack can provide significant gains.