Every interactive system requires a presentation mechanism, to show the user the data it handles. Often, the relationship between the data and its presentation is complex; further, it is often mediated by astyle mechanism, allowing the user or a designer to describe how the data should be displayed. It is a standing engineering challenge to develop a presentation model that is exible, handling many kinds of data and layout; powerful, giving the user extensive control over appearance; and e cient enough for interactive work. In this dissertation, we propose a model of presentation by tree transformation. Because information often has a hierarchical logical structure, trees are widely used to represent documents and other data. The layout or presentation of a document is also often modeled as a computation over a tree. But these trees are not generally identical. In other words, presentation can be seen as a mapping between trees. Casting it as a formal tree transformation o ers both expressive, compact style speci cations and e cient implementation. We present a general framework for presentation by tree transformation. It has been implemented as part of Ensemble, a software development environment and multimedia document system