This study examined the effects of a Web site design project on students' motivation and achievement. Tenth-grade biology students worked together in teams on an ecology project that required them to locate relevant information on the Internet, decide which information should be included on their Web site, organize the information into Web pages, and link the pages together. A comparison group received traditional ecology instruction that included lectures and labs. Data sources included motivation questionnaires, achievement tests, student attitude questionnaires, and teacher interviews. While both groups showed similar achievement gains, the students that designed Web sites were more motivated than the students that received traditional instruction. Advantages and disadvantages of the Web site design project are reported and discussed. The results of this study indicate that it is feasible for a high-school teacher to use a student-as-designer model of instruction with Web-based technology.