A program system has been developed as a tool for interactive analysis and design of multi-element airfoils in incompressible viscous flow. A global description of the system is given. It involves the application of three computational methods, one for the analysis of viscous flow and one for the analysis of inviscid flow around multi-element airfoils and one for the design of multi-element airfoils in inviscid flow. The latter two methods are described in some detail. The essential features of the design method are illustrated by means of numerical results.