INTRODUCTION The Khon or masked play is a classical form of Siamese drama.Originally all the actors except buffoons and those who impersonated women wore masks, namely, hollow figures of different shapes and colours being conventional representations of the heads and faces of ogres, monkeys, men and gods. But later on actors playing the pasts of men and gods too took to wearing crowns or tall pointed head-dress instead of masks. It is understood that the movements of the feet and the trunks of the actors impersonating ogres and monkeys were originally adopted from those of the fencers and of the persons who hold up the leather figures while staging the Siamese “Shadow – play” (an ancient form of entertainment like “Wayang Purwa” of Java) while the movements of their hands, arms, shoulders and heads as well as all the movements of those who play the parts of men, women and gods have been adopted from those of the actors of old Siamese dance-dramas and ballets. Masked plays have to make use of music and it, both vocal and instrumental, has been borrowed from drama of the “Lakon Nai” type. The instrumental music is provided by one kind of Siamese orchestra called “Piphat.” These features of Lakon Nai and the ballet which have made the masked play more elegant than before must have been adopted by the kings themselves, or by others according to the ideas of the former, while the drama was confined to the court. Therefore masked plays of this kind are known as “Khon-rong-nai,” that is to say,”Masked plays(Khon) which resemble Lakon Nai” or “Masked plays which the king maintains within (nai) the royal palace for his amusement” The masked plays which the Department of Fine Arts teaches students to acts, and arranges to be staged, are also of Khon-rong-nai type though they are divided into parts and provided with scenery appropriate to the places of action and the events mentioned in the story. Because of this new feature we may call the masked play in its modern form “Khon Chak,” that is to say, “Masked play provided with scenery,” as others have done before. Formerly the text of a masked play consisted of narration and dialogue-the narration in”Chabang” and “Yani” verses, and the dialogue in Rai-yao”, alliterative and rhyming lines of unequal length. When certain features of the dance-drama were introduced into the masked play, a kind of literary composition used with Lakon Nai came to be used with the masked plays too, making their texts beautiful pieces of art composed in many literary forms. The narrations and dialogues are recited and spoken not by the actors (since they wear masks which prevent them from doing so) but by somebody else. This is an important point in which the masked play differs from other forms of drama. While attending a masked play one listens to poetry in the form of narrations, dialogues, and songs describing the movements of the actors, and sweet instrumental music which marks time for the above, and sees acting of many types, which differ according to the class of each character, as well as the scenery.