Kemalism (Turkish: Kemalizm, also archaically Kamâlizm), also known as Atatürkism (Turkish: Atatürkçülük, Atatürkçü düşünce), or The Six Arrows (Turkish: Altı Ok), is the founding official ideology of the Republic of Turkey. Kemalism, as it was implemented by Mustafa Kemal Atatürk after the declaration of Republic in 1923, was defined by sweeping political, social, cultural and religious reforms designed to separate the new Turkish state from its Ottoman predecessor and embrace a Western-style modernized lifestyle, including the establishment of secularism/laicism (French: laïcité), state support of the sciences, free education, women's rights, and many more. Most of those were first introduced to and implemented in Turkey during Atatürk's presidency through his reforms.

Many of the root ideas of Kemalism began during the late Ottoman Empire under various reforms to avoid the imminent collapse of the Empire, beginning chiefly in the early 19th-century Tanzimat reforms. The mid-century Young Ottomans attempted to create the ideology of Ottoman nationalism, or Ottomanism, to quell the rising ethnic nationalism in the Empire and introduce limited democracy for the first time while maintaining Islamist influences. In the early 20th century, the Young Turks abandoned Ottoman nationalism in favor of early Turkish nationalism, while adopting a secular political outlook. After the demise of the Ottoman Empire, Atatürk, influenced by both the Young Ottomans and the Young Turks, as well as by their successes and failures, led the declaration of the Republic of Turkey in 1923, borrowing from the earlier movements' ideas of secularism and Turkish nationalism, while bringing about, for the first time, free education and other reforms that have been enshrined by later leaders into guidelines for governing Turkey.