In this paper we discuss the benefits of extending VRML by constraints and present a new way based on prototypes and scripting to implement this extension. Our approach is easy-to-use, extensible and it considerably increases the expressivity of VRML. Our implementation supports one-way equational and finite domain constraints. We demonstrate the use of these constraints by means of several examples. Finally we argue that in the long run constraints should become an integral part of VRML. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Virtual Reality; D.3.3 [Programming Languages]: Language Constructs and Features—Constraints