Musicology is the academic, research-based study of music, as opposed to musical composition or performance. Musicology research combines and intersects with many fields, including psychology, sociology, acoustics, neurology, natural sciences, formal sciences and computer science.

Musicology is traditionally divided into three branches: music history, systematic musicology, and ethnomusicology. Historical musicologists study the history of musical traditions, the origins of works, and the biographies of composers. Ethnomusicologists draw from anthropology (particularly field research) to understand how and why people make music. Systematic musicology includes music theory, aesthetics, pedagogy, musical acoustics, the science and technology of musical instruments, and the musical implications of physiology, psychology, sociology, philosophy and computing. Cognitive musicology is the set of phenomena surrounding the cognitive modeling of music. When musicologists carry out research using computers, their research often falls under the field of computational musicology. Music therapy is a specialized form of applied musicology which is sometimes considered more closely affiliated with health fields, and other times regarded as part of musicology proper.

The word musicology comes from Greek μουσική mousikē 'music' and -λογια -logia, 'domain of study'.

The 19th-century philosophical trends that led to the re-establishment of formal musicology education in German and Austrian universities had combined methods of systematization with evolution. These models were established not only in the field of physical anthropology, but also cultural anthropology. This was influenced by Hegel's ideas on ordering "phenomena" which can be understood & distinguished from simple to complex stages of evolution. They are further classified into primitive & developed sections; whereas the particular stages of history are understood & distinguished as ancient to modern. Comparative methods became more widespread in musicology beginning around 1880.

The parent disciplines of musicology include:

Musicology also has two central, practically oriented sub-disciplines with no parent discipline: performance practice and research, and the theory, analysis and composition of music. The disciplinary neighbors of musicology address other forms of art, performance, ritual, and communication, including the history and theory of the visual and plastic arts and architecture; linguistics, literature and theater; religion and theology; and sport. Musical knowledge is applied within medicine, education and music therapy—which, effectively, are parent disciplines of applied musicology.

Music history or historical musicology is concerned with the composition, performance, reception and criticism of music over time. Historical studies of music are for example concerned with a composer's life and works, the developments of styles and genres (such as baroque concertos), the social function of music for a particular group of people, (such as court music), or modes of performance at a particular place and time (such as Johann Sebastian Bach's choir in Leipzig). Like the comparable field of art history, different branches and schools of historical musicology emphasize different types of musical works and approaches to music. There are also national differences in various definitions of historical musicology. In theory, "music history" could refer to the study of the history of any type or genre of music, such as the music of India or rock music. In practice, these research topics are more often considered within ethnomusicology and "historical musicology" is typically assumed to imply Western Art music of the European tradition.

The methods of historical musicology include source studies (especially manuscript studies), palaeography, philology (especially textual criticism), style criticism, historiography (the choice of historical method), musical analysis (analysis of music to find "inner coherence") and iconography. The application of musical analysis to further these goals is often a part of music history, though pure analysis or the development of new tools of music analysis is more likely to be seen in the field of music theory. Music historians create a number of written products, ranging from journal articles describing their current research, new editions of musical works, biographies of composers and other musicians, book-length studies or university textbook chapters or entire textbooks. Music historians may examine issues in a close focus, as in the case of scholars who examine the relationship between words and music for a given composer's art songs. On the other hand, some scholars take a broader view and assess the place of a given type of music, such as the symphony in society using techniques drawn from other fields, such as economics, sociology or philosophy.