In this paper we show that application-aware adaptation, a collaborative partnership between the operating system and applications, offers the most general and effective approach to mobile information access.We describe the design of Odyssey, a prototype implementing this approach, and show how it supports concurrent execution of diverse mobile applications.We identify agility as a key attribute of adaptive systems, and describe how to quantify and measure it.We present the results of our evaluation of Odyssey, indicating performance improvements up to a factor of 5 on a benchmark of three applications concurrently using remote services over a network with highly variable bandwidth.This research was supported by the