Founded in 1920, Osasuna first reached Segunda División in 1932, making it to La Liga three seasons later.

The club achieved their first ever UEFA Cup qualification in 1985–86 after finishing sixth, eventually reaching the third round in the 1990–91 edition. Finishing last in 1993–94, the side spent six years in the second level.

After a stellar 2005–06 domestic campaign, Osasuna made history by finishing in fourth place – tied for best ever – synonymous with the chance of qualifying for the UEFA Champions League in the following season through play-off matches. This achievement was made all the more dramatic by the suspense that was maintained until the last day of the championship in which Osasuna and Sevilla FC were both vying for the fourth place. Both teams eventually ended the season with the same number of points but Osasuna got through due to their head-to-head record. However, Osasuna didn’t make it to the Champions League group phase, as they were eliminated by Hamburger SV in the third qualifying round, leaving the Navarrese to vie in the UEFA Cup for the fifth time in their history.

source: Wiki