The paper describes newly developed software called the AIDE Interaction Development Environment (AIDE). AIDE provides a straightforward, consistent methodology for designing and implementing new interactive interface systems for environmental software. AIDE combines a toolkit of utility subroutines for building individual interactive screens with instructions for developing two parallel products: a file containing all text, questions, and messages used in interactive communication, and a FORTRAN program containing the control strategy and sequencing instructions for interactions. The system provides an efficient means for storing and updating screen contents. The AIDE package is based on a re-evaluation of currently available tools and ideas for constructing a user interface. Accordingly, the manual draws on an expanding knowledge of the 'human factors' involved in effective design of man-machine interfaces.