Cathedral of Our Lady of the Assumption, Roman Catholic cathedral in Moncton, Canada

Cathédrale Notre-Dame de l'Assomption is a Roman Catholic building made of grey sandstone with a square bell tower rising approximately 67 meters high. It displays Gothic arch windows and traditional church elements positioned at the corner of St George Street.

The parish of Our Lady of the Assumption was founded in 1914 by Henri D. Cormier, and the cathedral was built on the foundations of its crypt-chapel. Archbishop Louis-Joseph-Arthur Melanson announced the project on 9 January 1938; architect Louis-Napoléon Audet of Sherbrooke designed it, and the Ambrose Wheeler company of Moncton began work on 24 April 1939. The cornerstone was blessed on 13 June 1939, and the building was inaugurated on 21 November 1940.

The cathedral is called the Monument of Acadian Recognition, dedicated to the Virgin Mary as patron of Acadia. Its stained glass windows summarise the history of the Acadian people, and a fourteen-station Way of the Cross in Venetian enamel and gold mosaic lines the interior walls. Statues in the nave are by Claude Roussel, who added two glass mosaics in 2006, one showing seven scenes from the life of the Virgin and the other Saint Anne, patron of the Mi'kmaq, with their links to the Acadians.

The cathedral stands at 226 St-Georges Street. A 2009 assessment found major repairs needed to the roof, foundation, bell tower and electrical system, and the building was considered for demolition or sale before Archbishop Valéry Vienneau backed its safeguarding in 2012. Visitors enter from St-Georges Street; the interpretation centre MR21 is housed inside.

A digital interpretation center called MR21 opened in 2019 within the building, offering interactive presentations about its history. This modern addition lets visitors explore the construction story in innovative ways.