This thesis addresses the problem of formatting complex documents with electronic tools. In particular, the two problems of incorporating illustrations and laying out tables are treated in depth. The notion of style, a way of maintaining consistency in a document, runs throughout the thesis. It helps manage the complexities of formatting both illustrations and tables. The thesis reviews the history of document composition systems, including early computer typesetting systems, document compilers, and integrated document composition systems. The concept of graphical style is introduced to extend the more traditional notion of document style to illustrations. The observation that graphical style does not adequately deal with the layout problem for illustrations leads to the investigation of a more concentrated layout problem for the special case of table formatting. A grid system is used to describe the table layout arrangement and a constraint solver provides the general layout engine for formatting tables as well as the basis for future interactive table design tools. Further research based on the style and table formatting models can be extended to mathematical typesetting and full page layout. A glossary of typesetting terms and an index to the thesis are provided to help the reader deal with the typographic terminology used in the thesis.