Today, with the proliferation of aﬀordable computing, people use multiple devices to fulﬁll their information needs. Designers approach each device platform individ- ually, without accounting for the other devices that users may also use. In many cases, the software applications on all the user’s devices are designed to be functional repli- cates of each other, often with an emphasis on keeping their form and function consistent with the same application on other device platforms. In this paper, we present the idea of a personal information ecosystem, an analogy to bio- logical ecosystems, which allows us to discuss the inter- relationships among users’ devices. Using the examples of now-ubiquitous web-enabled devices, we discuss how con- sidering the user’s ecosystem of devices as a holistic de- sign target gives designers and researchers a language to describe and discuss the design of applications that span multiple devices.