This paper presents an implemented, psychologicallyplausible parsing model for Government Binding theory grammars. I make use of two main ideas: (1) a generalization of the licensing relations of [Abney, 1986] allows for the direct encoding of certain principles of grammar (e.g. Theta Criterion, Case Filter) which drive structure building; (2) the working space of the parser is constrained to the domain determined by a Tree Adjoining Grammar elementary tree. All dependencies and constraints are locaiized within this bounded structure. The resultant parser operates in linear time and allows for incremental semantic interpretation and determination of grammaticaiity.