Detailed structural analysis, the extraction of the biologically relevant knowledge from a three-dimensional structure, is essential to understanding the biomedical implications of a structure determined using electron microscopy (EM). The long-term goal of QED Labs is to develop software that provides both structural biologists and general biologists with increased capabilities of structural analysis, allowing elucidation of more biomedically relevant structural knowledge by a larger number of people, thus yielding a greater understanding of the biomedical processes under study. In this proposal we aim to design a package that allows extensive structural analysis and visualization of macromolecular complexes by not only trained structural biologists, but also by novice users. This package will incorporate the tools necessary to perform biologically relevant structural analysis of structures determined from EM data. The proposed software will provide several innovative features. The most novel of these is the concept of a biologically relevant structure analysis and visualization package that is compatible with the user's training and background in biomedical research rather than just a three-dimensional graphics package. That is, the proposed software will present data to the user in a language and format that a biologist understands, rather than simply providing pretty pictures using the language of a computer scientist. To aid novice users, a user guidance system will be provided to enable structural analysis and visualization even for those not trained in such analysis. The result of this Phase I SBIR will be a specification and a prototype for one aspect of the visualization and analysis software package. The complete analysis and visualization package will be implemented in a Phase II SBIR.