The 1929 Barcelona International Exposition (also 1929 Barcelona Universal Exposition, or Expo 1929, officially in Spanish: Exposición Internacional de Barcelona 1929 was the second World Fair to be held in Barcelona, the first one being in 1888. It took place from 20 May 1929 to 15 January 1930 in Barcelona, Spain. It was held on Montjuïc, the hill overlooking the harbor, southwest of the city center, and covered an area of 118 hectares at an estimated cost of 130 million pesetas. Twenty European nations participated in the fair, including Germany, Britain, Belgium, Denmark, France, Hungary, Italy, Norway, Romania and Switzerland. In addition, private organizations from the United States and Japan participated. Hispanic American countries as well as Brazil, Portugal and the United States were represented in the Ibero-American section in Sevilla.

A world's fair, also known as a universal exhibition or an expo, is a large global exhibition designed to showcase the achievements of nations. These exhibitions vary in character and are held in different parts of the world at a specific site for a period of time, typically between three and six months.