The term "qualify" comes from the IJA's numbers endurance competitions, where a competitor must catch each object at least twice to qualify for an attempt with the next higher number or for a winning run. In numbers endurance competitons and official world records, the only catches counted are those made before the time when the first dropped object should have been caught. The highest numbers of props that have been qualified are 11 balls (by Alex Barron), 10 ball bounce, 10 rings, and 8 clubs.
Qualifying a pattern with any number of hands is defined in the IJA's numbers endurance competition rules as "keep[ing] the pattern going without a drop long enough for each hand to make as many catches as there are objects being juggled." By this definition a flash of a one-handed pattern would be a qualifying run, and qualifying a 2-person passing pattern would require four times as many catches as objects. (IJA numbers passing competition rules also require each person to make no more than one self throw in a row, so that most of the throws are passes.) A run of twice as many catches as objects in a 2-person pattern is called a half-qualify.
Qualifying after a trickEdit
Doing a trick "to a qualify" means qualifying the basic pattern (or another pattern) after doing the trick, which demonstrates that the trick was done well enough to be able to re-enter a stable pattern. In WJF competition, a qualify is usually required after doing certain tricks, such as 360s, to get points for the trick.
Qualifying a 360 or other spinning trick means juggling for at least twice as many catches as objects after spinning, in addition to catching the objects thrown before spinning. To qualify a 5 ball 5 up 360, a juggler must make at least 10 throws after spinning, and catch all of the first 10 throws made after spinning. Catching the objects thrown before the spin does not count as part of the qualify according to WJF rules.