We highlight two fundamental problems that degrade the throughput of wireless mesh networks today. First, severe performance degradation can occur when sources send more traffic than what the network can support. The degradation can be sharp even in a simple setting of a single flow that traverses a network of two links. Second, current routing protocols fail to identify high throughput routing paths even when they exist. The underlying culprit in both cases is interference that is fundamental to wireless networks. As a first step towards a solution, we develop a novel approach to systematically account for and control interference in the network. Our approach uses (an approximation of) a formal model of interference to estimate the maximum rate at which flows can safely send traffic without overloading the network. Simulation and testbed experiments show that it can improve network throughput by as much as 50-100% in some configurations.