This article investigates the historical semantics of the concept of modernity in the political thought and dramatic works of Grigor Yeqhikian by reconstructing its meaning through the ideological framework of the Hunchakian Social Democratic Party. Rather than adopting Reinhart Koselleck’s Conceptual History (Begriffsgeschichte) as its theoretical framework, the study draws methodological inspiration from its historical-semantic perspective while reconstructing the concept of modernity on the basis of the Hunchakian Party’s ideological principles, political documents, and historical experience. Modernity is therefore examined not as a fixed philosophical category but as a historically contingent political concept whose meaning is constituted through ideological discourse and political practice. Examining the concept of modernity and its successive interpretations within the history of Iranian dramatic literature is particularly significant because it constituted one of the conceptual foundations upon which modern Persian drama emerged. Consequently, every interpretation of modernity within this literary tradition simultaneously represents an interpretation of one of the constitutive concepts underlying the formation of modern Iranian dramatic literature. After arriving in Iran in 1910 as a representative of the Hunchakian Social Democratic Party, Grigor Yeqhikian became the first playwright in the history of Iranian drama to introduce socialist—and, more specifically, social democratic—thought into dramatic literature in a systematic and programmatic manner. Building upon this ideological foundation, he developed a distinctive understanding of modernity that informed both his political writings and dramatic works. Earlier playwrights, from Mirza Fath Ali Akhundzadeh to Mirzadeh Eshqi, likewise offered influential interpretations of modernity. None of them, however, grounded their conception of the modern in the social democratic ideology of the Hunchakian Party, nor did they share Yeqhikian’s broader intellectual and political objective of familiarizing Iran’s revolutionary generation with the principles of socialism and democracy through the medium of theatre. Within this intellectual and political milieu, Yeqhikian produced his dramatic works between 1924 and 1936, conceiving theatre not merely as a literary form but also as a mirror reflecting the virtues and deficiencies of human morality and as an instrument for the ethical cultivation of Iranian society. This conception of theatre cannot, however, be separated from his ideological commitments. His understanding of theatre—as well as his interpretations of history, politics, morality, and social reform—becomes fully intelligible only when situated within the broader horizon of his commitment to social democracy and the political programme of the Hunchakian Social Democratic Party. From this perspective, interpreting the meaning of modernity in Yeqhikian’s dramatic works necessarily begins with an examination of his political thought and, more specifically, the semantic field constituted by his socialist worldview. Accordingly, this study adopts a descriptive-analytical method. While drawing methodological inspiration from the historical-semantic perspective of conceptual history, its analytical framework is derived primarily from the historical development, ideological principles, and political documents of the Hunchakian Social Democratic Party rather than from Koselleck’s theoretical model. This approach makes it possible to establish, on the basis of historical evidence, the intellectual continuity between Yeqhikian’s political writings and dramatic works while reconstructing the historically situated meanings that the concept of modernity acquired within his socialist political thought. Following a concise historical account of the formation of the Hunchakian Social Democratic Party in Geneva, its subsequent activities in the Ottoman Empire, its introduction into Iran, and its contribution to the Iranian Constitutional Revolution, the article turns to Yeqhikian’s principal political writings, including The Constitution of the Iranian Social Democratic Party (1910), What Do the Social Democrats Say? (1910), The Contemporary Views of the Iranian Social Democrats (1911), and A Memorandum to All Iranians (1927). These texts constitute the principal corpus through which the ideological foundations of Yeqhikian’s dramatic works are reconstructed. Drawing upon the central themes articulated in these writings, the analysis is organized around the following conceptual categories: federalism and ethnic pluralism; justice conceived as equality; opposition to the bourgeoisie as a means of overcoming capitalism and private property; progress directed toward the realization of absolute equality; constitutional reform and the centrality of parliament as the institutional precondition for the legal realization of socialism; the rejection of Islamism as a political ideology; the significance of individual agency insofar as it contributes to socialist social transformation; and the primacy of the socialist common good over individual interests. Of Yeqhikian’s numerous dramatic works, only four plays have survived: The War of the East and the West (1922), Anushirvan the Just and Mazdak (1924), The Field of Terror (1929), and Who Is Right? (1929). The present study therefore confines its analysis to these four extant plays. Across these plays, the concept of modernity is articulated through a distinctive semantic constellation whose constituent concepts vary according to each dramatic context. In The War of the East and the West, modernity is associated with the homeland, the Iranian nation, constituent nations, the separation of powers, historical consciousness, progress, science, independence, the new monarchy, and ancient Iran. In Anushirvan the Just and Mazdak, the concept is structured around justice, parliament, and revolution. In Who Is Right, modernity is articulated through women, individual rights, and freedom, whereas in The Field of Terror it is expressed through peace, war, and individual will. The meaning of modernity is simultaneously constituted through a corresponding constellation of counter-concepts (Gegenbegriffe), which delineate its semantic boundaries. These counter-concepts fall into two categories. The first appears in The War of the East and the West and derives from the semantic field of premodernity. Here, modernity is defined in opposition to such concepts as the East, obsolete knowledge, and the old monarchy, each representing elements of the premodern political and intellectual order. The second category emerges from within the semantic horizon of modernity itself. Rather than functioning as external opposites rooted in the premodern past, these counter-concepts represent rival articulations of modernity. In The War of the East and the West, they include the West, Alexander, foreign models of progress, justice, and collective ownership. These concepts therefore function not simply as conceptual opposites but as competing interpretations of the modern that contest Yeqhikian’s socialist understanding of modernity. A comparable semantic structure appears in Who Is Right? and The Field of Terror. In these plays, the counter-concepts emerge exclusively from within modernity itself and constitute what may be described as its negative modality. Although they present themselves as manifestations of the modern, they continue to reproduce social relations inherited from the premodern order. Within this semantic field, justice, the merchant, the bourgeoisie, and war function as counter-concepts, exposing the contradictions of bourgeois modernity by revealing the persistence of premodern structures beneath an ostensibly modern political and social vocabulary. Within this framework, modernity in Yeqhikian’s dramatic works signifies a fundamental reconfiguration of the bourgeois political and social order in accordance with the ideological principles of Hunchakian social democracy. From Yeqhikian’s perspective, bourgeois modernity perpetuates inherited modes of thought and premodern forms of social consciousness under modern historical conditions, thereby obstructing the realization of justice. Modernity consequently presupposes not only the recognition of individual political agency and the collective rights of historically constituted ethnic communities but also the constitutional institutionalization of freedom, equality, and the rights of nations. Here, the term nation is employed in the early twentieth-century socialist sense adopted by Yeqhikian and the Hunchakian Social Democratic Party, referring to collective political communities rather than sovereign nation-states. Within this conceptual framework, parliament functions as the institutional embodiment of collective deliberation and political participation, standing in opposition to the individualism characteristic of bourgeois society. Accordingly, whenever Yeqhikian’s plays—particularly The War of the East and the West and Anushirvan the Just and Mazdak—invoke the idea of Iran, it should not be interpreted as denoting a culturally homogeneous nation-state. Rather, Iran is conceived as a political community composed of multiple historically constituted ethnic communities—or, in Yeqhikian’s socialist vocabulary, multiple nations. National unity therefore depends upon the equal recognition of these constituent communities and their participation in a representative parliamentary order. Equality-based justice thus becomes the constitutional principle through which political unity is achieved without erasing historical and ethnic diversity. From this perspective, the realization of socialist justice does not imply the fragmentation of Iran as a political entity. Rather, it presupposes recognition that the country’s constituent nations—understood in Yeqhikian’s early twentieth-century socialist vocabulary as historically constituted ethnic communities rather than sovereign nation-states—have long existed within Iran as distinct ethnic and tribal collectivities. Socialist justice therefore requires that their collective rights be incorporated into a constitutional order founded upon equality. National unity, in this formulation, is conceived not as the erasure of diversity but as the political outcome of its equal constitutional recognition. A further defining characteristic of Yeqhikian’s conception of modernity is that it does not reject the past merely because it belongs to the past. Rather, those elements of the historical tradition that embody principles compatible with socialism are preserved and reinterpreted as normative resources for imagining a future founded upon absolute equality. The past is therefore neither restored nor idealized; instead, it functions as a historical reservoir from which socialist modernity derives both historical continuity and normative legitimacy. The realization of such a future also requires that freedom be understood primarily in its negative dimension. Socialist ideals become attainable only through the negation of entrenched structures inherited from both the premodern order and bourgeois modernity. Only by overcoming these historical forms of domination can socialist principles be extended to all Iranian peoples and communities. Within this conception of modernity, neither religious domination nor capitalist hegemony possesses normative legitimacy, since individuals are expected to define themselves in relation to the socialist common good rather than private interest. Individuality is therefore meaningful only insofar as it is conditioned by the ideal of absolute equality. Consequently, individualism is never accorded normative priority but remains subordinate to the ethical and political imperatives of socialism. Only under these conditions can a specifically socialist form of modernity—the normative horizon of Yeqhikian’s social democratic project—be realized.