SMLserver is an effcient multi-threadedWeb server platform for Standard ML programs. It provides access to a variety of different Relational Database Management Systems (RDBMSs), including Oracle, MySQL, and PostgreSQL. We describe the execution model and the region-based memory model of SMLserver and explain our solutions to the design issues we were confronted with in the development. We also describe our experience with programming and maintaining Web applications using Standard ML, which provides higher-order functions, static typing, and a rich module system. Through experiments based on user scenarios for some common Web tasks, the paper demonstrates the efficiency of SMLserver, both with respect to script execution and database connectivity.