A class skill is a skill that is closely related to the role of a given class, making it easier for that class to learn that skill. (Each class has its own list of class skills.) The opposite of a class skill is a cross-class skill. The difference between "class" and "cross-class" is determined based on the class being advanced during level-up.

It takes one skill point to add a rank in a class skill. The highest the ranks in a class skill can be raised to is character level plus three.