ADE-4 is a multivariate analysis and graphical display software designed for Apple Macintosh and Windows 95 computers. It consists of several standalone modules offering a wide range of multivariate analysis methods, from simple one-table analysis to three-way table analysis and two-table coupling methods. The software provides various graphical display options, including automatic collection of elementary graphics for data tables and geographical mapping. A dynamic graphic module allows interactive operations such as searching, zooming, point selection, and displaying data values on factor maps. The user interface is simple and homogeneous, making ADE-4 easy to use for non-specialists in statistics, data analysis, or computer science. ADE-4 is composed of two types of modules: computational and graphical. Computational modules have an 'Options' menu to select analysis methods, such as principal component analysis (PCA) on correlation or covariance matrices. A dialog window allows users to input parameters, and a progress window shows the status of long computations. A text report is generated at the end of the analysis. Graphical modules also have an 'Options' menu to choose graphic types and a 'Windows' menu for interactive parameter definition. The main dialog window allows selection of input files and parameters, while other windows control graphic content and format. ADE-4 is accessible via a HyperCard (Macintosh) or WinPlus (Windows 95) stack (ADE-4•Base), which displays files in the current data folder and allows navigation through two other stacks: ADE-4•Data and ADE-4•Biblio. ADE-4•Data includes over 150 example data sets from environmental studies, while ADE-4•Biblio contains over 800 references on statistical methods and data sets available in ADE-4. The software is freely available on the internet and is suitable for use in various scientific disciplines, including environmental, social, chemical, and geological sciences.ADE-4 is a multivariate analysis and graphical display software designed for Apple Macintosh and Windows 95 computers. It consists of several standalone modules offering a wide range of multivariate analysis methods, from simple one-table analysis to three-way table analysis and two-table coupling methods. The software provides various graphical display options, including automatic collection of elementary graphics for data tables and geographical mapping. A dynamic graphic module allows interactive operations such as searching, zooming, point selection, and displaying data values on factor maps. The user interface is simple and homogeneous, making ADE-4 easy to use for non-specialists in statistics, data analysis, or computer science. ADE-4 is composed of two types of modules: computational and graphical. Computational modules have an 'Options' menu to select analysis methods, such as principal component analysis (PCA) on correlation or covariance matrices. A dialog window allows users to input parameters, and a progress window shows the status of long computations. A text report is generated at the end of the analysis. Graphical modules also have an 'Options' menu to choose graphic types and a 'Windows' menu for interactive parameter definition. The main dialog window allows selection of input files and parameters, while other windows control graphic content and format. ADE-4 is accessible via a HyperCard (Macintosh) or WinPlus (Windows 95) stack (ADE-4•Base), which displays files in the current data folder and allows navigation through two other stacks: ADE-4•Data and ADE-4•Biblio. ADE-4•Data includes over 150 example data sets from environmental studies, while ADE-4•Biblio contains over 800 references on statistical methods and data sets available in ADE-4. The software is freely available on the internet and is suitable for use in various scientific disciplines, including environmental, social, chemical, and geological sciences.