Many complex applications use a Web browser as their main user interface. However, Web application development still remains difficult today and lags behind conventional desktop application development. Seaside is a Web application framework that provides a uniform, pure object-oriented view for Web applications. Exploiting the reflective features of Smalltalk, Seaside reintroduces procedure call abstraction in a client-server context. By harnessing Smalltalk's dynamic nature and reflective capabilities, Seaside is able to incorporate key features such as a component architecture that supports multiple, simultaneously active control flows; programmatical XHTML generation; and on-the-fly debugging, code editing, and recompilation. This article is part of a special issue on dynamically typed languages.