This manual includes in an improved and supplemented form the 'Notes for the Teaching of Compulsory Harmony' that I have been providing to my students for many years in the form of photocopied manuscripts. These notes have been widely circulated outside the framework of the Athens Conservatory, and I have often been encouraged to proceed with a more systematic publication of them. Since I believed and still believe that the publication of yet another Harmony book would have nothing new to offer in our time, but knowing that the existing manuals are intended, with few exceptions, for the teaching of 'special harmony', I preferred to gather in this work what is needed for the course of 'Compulsory' Harmony to the extent that: a) it equips the student - music performer with the terminology and basic knowledge that will be needed to meet the requirements of the Music Morphology course and the needs of harmonic analysis of the works they are going to perform, but also: b) prepares the student - theorist by providing them with a first, as good as possible, acquaintance with the material that will be needed for the continuation of their studies in 'Special' and generally in Higher Theoretical Studies. [...] [Excerpt from the preface text]