Day of the Institutions is a public regional holiday that is observed solely in the autonomous community of Cantabria in Spain. The holiday is dedicated to celebrating the establishment of Cantabria on the 28th of July, 1778.

The festivities of the Day of the Institutions are rather quiet, and they include sports competitions and communal meals. Moreover, the streets, houses, and buildings are usually decorated with the flag of Cantabria.

On that day, the general public takes the day off, and most organizations, businesses, and stores are closed. Some bakeries and grocery stores, however, are usually open. Whereas public transports are usually running –except in rural areas– albeit to a reduced timetable. If the holiday falls on a Sunday, the authorities usually push it to a different day. In case of falling on a working day two days prior to, or subsequent to, a weekend holiday, many businesses and organizations usually take the in-between day off, as well.