This Keystone Symposia conference will focus on novel insights into respiratory virus biology that may ultimately lead to more effective prevention and treatment strategies. In many cases, these novel insights are made possible by new tools that are now available to study pathogens whose infectious cycle is largely restricted to the airways. New information about virus-host interactions will be discussed, as well as the interplay among diverse microorganisms present in the host airways. The long-term ramifications of respiratory virus infections beyond acute disease will be explored along with both recent successes and failures in prevention and treatment. This conference is a joint symposium with Viral Immunity: Basic Mechanisms and Therapeutic Applications and will have a few combined sessions.