In order to support mobile computing research, including the development of software which will allowseamless access to multiple wireless data networks, we are building a wireless data network infrastructureat Carnegie Mellon University. This infrastructure will allow researchers and other members of the campuscommunity to use mobile computers to gain access to data networks while they are on-campus or while theyare off-campus in the greater Pittsburgh area. The infrastructure will initially include two different typesof wireless networks, a low-bandwidth wide area system and a high-bandwidth local area system, each ofwhich will provide access to our campus computer network. Since our campus network is called “Andrew”(after Andrew Carnegie and Andrew Mellon), the new wireless infrastructure has been dubbed “WirelessAndrew.” This article describes the Wireless Andrew infrastructure we are building. We begin with an overview of the infrastructure and the characteristics of the two types of wireless networks we are using. Next, wedescribe in more detail each of these networks. We discuss the technology used, our implementation of itin our wireless network infrastructure, and our current deployment experience. Finally, we summarize thelessons we have learned and present conclusions.