The Tinkertoy graphical interface to Lisp is described, in which programs are 'built' rather than written, out of icons and flexible interconnections. It represents a computer/user interface that can easily exceed the interaction speed of the best text-based language editors and command languages. It also provides a consistent framework for interaction across both editing and command execution. Moreover, because programs are represented graphically, structures that do not naturally conform to the text medium can be clearly described, the new kinds of information can be incorporated into programs and program elements.>