ABSTRACT This thesis investigates how change of states is expressed in Taiwan Sign Language (TSL). Two main issues will be discussed in this thesis. First, we attempt to find out the various classifier constructions for expressing change of states in TSL. Second, from a cognitive perspective, we try to find out the construings behind the different expressing forms. The first issue is concerned with the constructions for expressing change of states. In TSL, the information carried by the lexical item BREAK could be as vague as that in spoken languages. However, expressed through the classifier constructions, TSL could give us more information about how the object is changed from one state to another. Our data of TSL show a tendency to express change of states through classifier construction. They also show how lexical items and classifiers collaborate together to express change of states and the expression. The collaboration is achieved through (a) classifier predicates, (b) both a lexical item and a classifier predicate, and (c) merging a lexical item and a classifier predicate. When objects are expressed through whole entity classifiers, bodypart classifiers could also be used together for the ease of perception. Tentative explanations are then given for these observations. The second issue concerned is the cognition behind the different expressions. Three cognitive concepts are proposed to help us generalize our data: whole to parts, disappearance, and deformation. Concepts of whole to parts are further categorized into two: individual to parts and collection to pieces. Two reasons for the application of different methods can be offered: One is the application of one hand or two hands. The other is the perspective difference—taking the whole changing process or only the resultant state. A direct modulation on the hand configuration is adopted for depicting the whole changing process. In contrast, when the depictive method is applied, the resultant state is depicted without changing process. Through the deformation concepts, we observe that physical constraints could also result in the application of different methods. These methods accords with those identified by Sutton-Spence and Woll (1999). From the disappearance concepts, we learn that manners in sign language could be expressed through the resultant classifier construction. The speed of the changing process could be perceived through the resultant classifier construction to indicate durational, instantaneous and other states of change. Key words: Taiwan Sign Language (TSL), change of states (COS), classifier, classifier construction