As the new theoretical developments occur in the field of construction of language recognizers, corresponding tools became necessary to allow practical implementation of the proposed theories. Such recognizer development tools are required to present characteristics similar to commercially found programming environments. Our tool, called RSW, has been designed to provide its users with an integrated environment for editing, compiling, executing, debugging and optimizing recognizers based on the theory of finite-state-, pushdown- and adaptive-automata. RSW version 1.0 is now available for use on IBM-PC-compatible machines.