In web-based applications, the dialog control logic is often hidden in or entwined with the presentation and/or application logic, even if the latter tiers are well-separated. This makes it difficult to control complex dialog structures like nested dialogs, and to reconcile the device-independent business logic with the device-specific interaction patterns required by different clients' I/O capabilities. To avoid continuous re-implementation of the dialog control logic, we present a Dialog Control Framework that is separate from the presentation and business tiers, and manages arbitrarily nested dialog flows on different presentation channels. The framework relies on dialog specifications developed using the Dialog Flow Notation, which are translated into an object-oriented dialog flow model for efficient run-time lookups. This way, the framework automates the dialog control aspect of web-based application development and leaves only the tasks of implementing the business logic, designing the hypertext pages, and specifying the dialog flow to the developer.