In 1974, three years after undertaking the organization of Inter-Cities Fairs Cup, UEFA devised a classification system for countries in order to assign the number of berths in UEFA Cup (C3), depending on the progress of their teams in European competitions. In Fairs Cup (the predecessor of C3) the clubs participated only by invitation, and UEFA wanted to establish a regular access system based on the final classification in domestic Leagues. This problem didn't exist in the other two European tournaments, Champions Cup (C1) and Cup Winners' Cup (C2), in which only winners of domestic Leagues and Cups could participate. Although UEFA Country Ranking (UCR) was intended originally to assign berths in C3, it was later extended to include Intertoto Cup (IC) and Champions League (C1).

UCR is a ranking of countries made with the scores of their teams in C1, C2, and C3 during 5-year periods (quinquennium, plural quinquennia). UEFA awards 2 points per win and 1 point per draw; additionally, 1 bonus point is given to clubs reaching the rounds of 1/4 Finals, Semifinals, and Final. During seasons 1991-92, 1992-93, and 1993-94, 2 extra points were awarded to teams reaching the Group Stage of Champions League, which became just 1 point from season 1994-95 on. Starting in season 1999-2000, after the disappearance of C2 and the subsequent increase of rounds in C3, UCR underwent a slight modification: the assignment of points remained basically the same, except that in Qualifying Rounds of C1 and C3 points are "halved:" 1 point per win, 0.5 points per draw. From season 2004-05 on, with the new re-shape of C1 and C3, teams qualifying for the First Knock-Out Round of Champions League will be awarded an extra bonus point. Besides, to compensate for the lesser number of games in relation to past seasons, the teams qualified for the Group Stage of C1 are awarded 3 extra points (instead of just 1, like before).

At the end of every season, UEFA establishes a yearly ranking of countries. Each country is assigned the average of all the points earned by its participating teams in C1, C2, and C3 of a single season. The sum of five consecutive seasons represents the UCR at the end of that quinquennium. This ranking determines the number of berths assigned to each country in UEFA Cup (C3) corresponding to the second season after the one that closes the 5-year period, so that all the countries know at the beginning of their domestic championships how many berths in C3 they have for the next season. For example, the UCR of the period 1991-95 (made with the points earned from season 1990-91 through 1994-95) determines the berths in UEFA Cup 1996-97 and Intertoto Cup 1996.

The distribution of berths in C3 from the inception of UCR until the quinquennium 1993-97 was as follows:

· Countries ranked in places 1-3: 4 berths.

· Countries ranked in places 4-8: 3 berths.

· Countries ranked in places 9-21: 2 berths.

· Rest of countries: 1 berth.

From quinquennium 1994-98 on (in order to account for the merge of UEFA Cup and Cup Winners' Cup, starting in season 1999-2000), the next assignment is applied to C1 and C3:

· Countries ranked in places 1-3: 4 berths in C1 / 3 berths in C3.

· Countries ranked in places 4-6: 3 berths in C1 / 3 berths in C3.

· Countries ranked in places 7-8: 2 berths in C1 / 4 berths in C3.

· Countries ranked in places 9-15: 2 berths in C1 / 2 berths in C3.

· Countries ranked in places 16-21: 1 berth in C1 / 3 berths in C3.

· Rest of countries: 1 berth in C1 / 2 berths in C3.

From quinquennium 2004-08 on (starting in season 2009-10), following the re-shaping of the UEFA Cup format into the new Europa League in the summer of 2009, the assigment of berths for C3 is substantially changed, so that all countries will now receive 3 berths each (except those ranked 7-9, with 4 berths, and Andorra, Liechtenstein and San Marino, with only 1 berth).

From quinquennium 2006-2010 on (once the newly formatted season 2009-2010 is added), the calculation of UCR underwent some new modifications, which can be summarized as follows:

CALCULATION OF UCR (from season 2009-2010 on):

· 2 pts. per victory / 1 pt. per draw (these points are halved, however, during the qualification rounds of C1 and C3 before the Group Stage).

· 1 bonus point for reaching each of the final rounds of C1 and C3 (1/4 Final, 1/2 Final and Final).

· 4 bonus points for reaching the Champions League phase (Group Stage) of C1.

· 5 bonus points for reaching the First Knock-Out Round of C1.