Rappelz features a variety of classes, most of which can be unlocked through attaining a certain character level and job level. Character levels are attained in the traditional way, by defeating mobs and gaining experience points. Besides experience points, defeating mobs also grants the player job points. Job points are required to obtain and level up the character's skills, but also to increase their job level. Most skills require a minimum job level to be unlocked.

There are three class categories in Rappelz: starting class, first job class and second job class. After attaining level 10 and job level 10, characters can choose one of the first job specialized classes. At level 50 and job level 40, the second job class can be chosen. All classes of any race share a single "racial skill" which grows in power with each class increase. When advancing a character's job class, the job level is reset.

It is also possible to 'overbreed' your character. This means the character is not advanced to a second job class when it reaches level 50, job level 40. Instead, job points are collected to bring the job level up to level 50 as well, before further specializing. Overbreeding gives a character a small bonus to its statistics. Opinions vary on whether overbreeding is worth the amount of time and job points spent.