In this thesis, an interactive user interface builder is designed and implemented with the Serpent UIMS and Motif toolkit. An Interactive Dialogue Editor is designed to help interface designer define static layout of interface components. A Structure Editor is also designed to specify the dynamic behavior of the interface. OSF/Motif``s User Interface Language is extended with methods and variables to embed application functionality into the presentation description language. Runtime environment of this Interface Builder is constructed following that of the Serpent system.