Comparative literature studies is an academic field dealing with the study of literature and cultural expression across linguistic, national, geographic, and disciplinary boundaries. Comparative literature "performs a role similar to that of the study of international relations but works with languages and artistic traditions, so as to understand cultures 'from the inside'". While most frequently practised with works of different languages, comparative literature may also be performed on works of the same language if the works originate from different nations or cultures in which that language is spoken.

The characteristically intercultural and transnational field of comparative literature concerns itself with the relation between literature, broadly defined, and other spheres of human activity, including history, politics, philosophy, art, and science. Unlike other forms of literary study, comparative literature places its emphasis on the interdisciplinary analysis of social and cultural production within the "economy, political dynamics, cultural movements, historical shifts, religious differences, the urban environment, international relations, public policy, and the sciences".

Students and instructors in the field, usually called "comparatists", have traditionally been proficient in several languages and acquainted with the literary traditions, literary criticism, and major literary texts of those languages. Many of the newer sub-fields, however, are more influenced by critical theory and literary theory, stressing theoretical acumen and the ability to consider different types of art concurrently over proficiency in multiple languages.

The interdisciplinary nature of the field means that comparatists typically exhibit acquaintance with sociology, history, anthropology, translation studies, critical theory, cultural studies, and religious studies. As a result, comparative literature programs within universities may be designed by scholars drawn from several such departments. This eclecticism has led critics (from within and without) to charge that comparative literature is insufficiently well-defined, or that comparatists too easily fall into dilettantism because the scope of their work is, by definition, broad. Some question whether this breadth affects the ability of PhDs to find employment in the highly specialized environment of academia and the career market at large, although such concerns do not seem to be borne out by placement data, which shows comparative literature graduates to be hired at similar or higher rates than English literature graduates.

The terms "comparative literature" and "world literature" are often used to designate a similar course of study and scholarship. Comparative literature is the more widely used term in the United States, with many universities having comparative literature departments or comparative literature programs.

Comparative literature is an interdisciplinary field whose practitioners study literature across national borders, time periods, languages, genres, boundaries between literature and the other arts (music, painting, dance, film, etc.), and across disciplines (literature and psychology, philosophy, science, history, architecture, sociology, politics, etc.). Defined most broadly, comparative literature is the study of "literature without borders". Scholarship in comparative literature includes, for example, studying literacy and social status in the Americas, medieval epic and romance, the links of literature to folklore and mythology, colonial and postcolonial writings in different parts of the world, and asking fundamental questions about the definition of literature itself. What scholars in comparative literature share is a desire to study literature beyond national boundaries and an interest in languages so that they can read foreign texts in their original form. Many comparatists also share the desire to integrate literary experience with other cultural phenomena such as historical change, philosophical concepts, and social movements.

The discipline of comparative literature has scholarly associations such as the International Comparative Literature Association (ICLA) and comparative literature associations in many countries. There are many learned journals that publish scholarship in comparative literature: see "Selected Comparative Literature and Comparative Humanities Journals". For a list of books in comparative literature, see "Bibliography of (Text)Books in Comparative Literature".

Work considered foundational to the discipline of comparative literature include Spanish humanist Juan Andrés's work, Transylvanian Hungarian Hugo Meltzl de Lomnitz's scholarship, also the founding editor of the journal Acta Comparationis Litterarum Universarum (1877) and Irish scholar H.M. Posnett's Comparative Literature (1886). However, antecedents can be found in the ideas of Johann Wolfgang von Goethe in his vision of "world literature" (Weltliteratur) and Russian Formalists credited Alexander Veselovsky with laying the groundwork for the discipline. Viktor Zhirmunsky, for instance, referred to Veselovsky as "the most remarkable representative of comparative literary study in Russian and European scholarship of the nineteenth century" (Zhirmunsky qtd. in Rachel Polonsky, English Literature and the Russian Aesthetic Renaissance [Cambridge UP, 1998. 17]; see also David Damrosch During the late 19th century, comparatists such as Fyodor Buslaev were chiefly concerned with deducing the purported Zeitgeist or "spirit of the times", which they assumed to be embodied in the literary output of each nation. Although many comparative works from this period would be judged chauvinistic, Eurocentric, or even racist by present-day standards, the intention of most scholars during this period was to increase the understanding of other cultures, not to assert superiority over them (although politicians and others from outside the field sometimes used their works for this purpose).^{[citation needed]}