Pad Thai is a dish of stir-fried rice noodles with eggs, fish sauce , tamarind juice, red chilli pepper, plus any combination of bean sprouts, shrimp, chicken, or tofu, garnished with crushed peanuts and coriander. It is normally served with a piece of lime, the juice of which can be added along with Thai condiments. Pad Thai is one of Thailand's national dishes.

Two different styles of Pad Thai have evolved: the version most often found in the streets of Thailand, which is relatively dry and light, and the version that seems dominant in many restaurants in the West, which is heavier and may be covered in red oil.

Though the dish had been known in various forms for centuries – it is thought to have been brought to the ancient Thai capital of Ayuthaya by Vietnamese traders – it was first made popular as a national dish by Luang Phibunsongkhram when he was prime minister during the 1930s and 1940s, partly as an element of his campaign for Thai nationalism and centralization, and partly for a campaign to reduce rice consumption in Thailand. The Thai economy at this time was heavily dependent on rice exports; Phibunsongkhram hoped to increase the amount of it available for export by launching a campaign to educate the poor in the production of rice noodles, as well as in the preparation of these noodles with other ingredients to sell in small cafes and from street carts.

Its name literally means "Thai-style stir-fried noodles", which suggests an origin that isn't Thai. Indeed, noodle cookery in most Southeast Asian countries was introduced by the wave of immigrants from southern China settling in the region the past century. They brought with them rice noodles and their ways of cooking them. During the recession following World War II, the post-war government of Field Marshall Pibul, desperate in its efforts to revive the Thai economy, looked for ways to stem the massive tide of unemployment. Among the occupations the government aggressively promoted to give the populace a way to earn a living was the production of rice noodles and the operation of noodle shops. Detailed instructions on how to make the noodles and recipes were printed and distributed around the country. From these efforts, rice noodles became firmly rooted in the country and have since become a widespread staple food.

Outside of Thailand, Pad Thai is one of the best-known Thai dishes, and is very popular in Thai restaurants in the United States and Australia.