The purpose of this chapter is to include for consideration and study those essential factors which influence architectural design. In so brief a space only principles can be stated but by study of the books included in the references at the end of the chapter sufficient knowledge of the subject may be obtained to understand the principles of architectural design and to appreciate architectural beauty. The study of houses of good design and also the study of photographs and illustrations of well-designed and attractive homes are of exceptional value in developing appreciation. A list of books containing such illustrations has been included for this purpose.