This dissertation is an investigation into the concept of national days of the Republic of Turkey and it focuses on their establishment, alteration, instrumentalization as well as their commodification over time. The national days have always been a controversial issue in Turkish political life. Adopted as a part of Turkish nation building after the War of Independence between 1919 and 1922, the concept of national days and state rituals allow for a realm of interpretation of the tension between secular and religious worldviews. Beyond the research of the history of their establishment on an administrative level, this dissertation intends to demonstrate how they were embraced or criticised by the Turkish society. It will fill the gap of an extensive study on Turkish national days and create an opportunity to evaluate modern Turkish political history through national days. On a social level, the analysis relies on a variety of resources including but not limited to video archive, photographs, postcards, newspapers, interviews, written correspondence, while postal stamps, posters, archives, and records of parliamentary sessions inform the administrative level. Keywords: national days of Turkey, celebration and mourning practices, rituals, myths, cult of Atatürk, nationalism, secularism, religion.