Pakistan Day (Urdu: یوم پاکستان‎, lit. Yaum-e-Pakistan) or Pakistan Resolution Day, also Republic Day, is a national holiday in Pakistan commemorating the Lahore Resolution passed on 23 March 1940 and the adoption of the first constitution of Pakistan during the transition of the Dominion of Pakistan to the Islamic Republic of Pakistan on 23 March 1956 making Pakistan the world's first Islamic republic. A Republic Day parade by the armed forces is often part of the celebrations.

The day celebrates the adoption of the Pakistan resolution by the Muslim League at the Minar-e-Pakistan (lit. Pakistan Tower) that called for establishing an independent federation comprising provinces with Muslim majority located in north-western and north-eastern region of British controlled territories in India (excluding autonomous princely States) on 23 March 1940.In this day a resolution was passed saying that Muslims in India wanted independence and separate homeland and they were persecuted in India. Since then, the day is celebrated annually throughout the country as a public holiday. The Armed Forces of Pakistan usually hold a military parade to celebrate the event.