This research analyzes the decline and the defeat of leftist movements in Iran and Turkey in a comparative historical perspective. The relatively easy defeat against the state apparatuses, resulting in the destruction of the organized Left, has led to common academic and public misconceptions that the Left has not been influential. Most of the existing academic literature contextualized these defeats almost exclusively in their native contexts. These explanations often produced common arguments such as “inability to reach the masses”, “ideological and theoretical poverty”, “factionalism”, “over-reliance on determinism”, or “over-reliance on a foreign theory”. While these factors have undeniably played a part in the eventual defeat of the Left by brutal state repression, they do not necessarily explain why the organized Left could not resurface as it did in previous defeats such as after the in 1953 Anglo-American Coup in Iran or the 1971 Coup in Turkey. Such overlaps in academic explanations point to the necessity of a comparative analysis, primarily because the conditions in which the state crushed the organized Left was considerably different. Relying on a study of selected leftist intellectuals and groups, including Khalil Maleki, Jalal Al-e Ahmad, and Fedayeen-e Khalq from Iran and Naz?m Hikmet, Hikmet K?v?lc?ml? and Dev-Genç from Turkey, I show that three domestic factors strongly contributed to the making of leftist politics: the Left’s experiences with and understanding of the authoritarian modernisms of Reza Shah Pahlavi and Mustafa Kemal Atatürk; the Left’s understanding of the socioeconomic divides in their domestic contexts; and finally, the Left experiences with state securitization and violence. While I do not contradict the existing explanations, I add that the decline of Marxist-Leninist Left’s influence was also the result of a longer process of hegemonic struggle where the Marxist-Leninist model, similar to the global context, failed against right-wing, religious ideologies and eventually lost its hegemony over anti-systemic movements. Democratic deficits of the organized Left, including gender/sexuality and ethnicity based critiques, strongly contributed to this process. Finally, I claim that although the state effectively crushed the organized anti-systemic opposition and the Marxist-Leninist model lost its hegemony over progressive movements, native determinants of leftist politics maintained their relevance among oppositional social blocs. This results in a continuity of leftist narratives and demands in contemporary progressive/leftist oppositional politics.