The emergence of networked devices in the home has made it possible to develop applications that control a variety of household functions. However, current devices communicate via a multitude of incompatible pro- tocols, and thus gateways are needed to translate between them. Gateway construction, however, requires an intimate knowledge of the relevant pro- tocols and a substantial understanding of low-level network programming, which can be a challenge for many application programmers. This paper presents a generative approach to gateway construction, z2z, based on a domain-specific language for describing protocol behaviors, mes- sage structures, and the gateway logic. Z2z includes a compiler that checks essential correctness properties and produces efficient code. We have used z2z to develop a number of gateways, including SIP to RTSP, SLP to UPnP, and SMTP to SMTP via HTTP, involving a range of issues common to protocols used in the home. Our evaluation of these gateways shows that z2z enables communication between incompatible devices without increasing the overall resource usage or response time.