Advances in PC programming systems allow the development of highly interactive engineering design software. Software can work in a way which is obvious to the user, and gives considerable feedback during and after the analysis. If an indication is given of the cost of a design, the user can concentrate on making design decisions, rather than on the mechanics of the analysis. Such programs can be developed to run themselves, making changes to the data and carrying out analysis until an optimum design has been reached. These possibilities are illustrated using a program for the design of reinforced soil structures.