Arc the Lad has an interesting leveling system. Characters gain experience for every action they take, with the exception of moving, and also when they take damage or are affected by a magical spell cast by another. The amount of experience recieved is determined by level.

Experience Chart

Action	Experience
Attack Physically	=Target Level x2
Defeat Target Physically	=Target Level x 12
Recieve Physical Attack	=Character Level
Use Ability/Magic	=Sum of levels of those affected
Affected by Ability/Magic	=Character Level/3 (Round fractions up)
Defeat Target with Ability/Magic	=Target Level x11
Use Item	=Character Level x3
Open Treasure Chest (Item)>	22 exp.
Open Treasure Chest (Accessory)>	202 exp.

This is actually a lot simpler than it may seem. For instance, Arc defeats a Dream Cloud, which is level 3. To figure out the experience gained, we simply multiply 3x12; voila, Arc recieves 36 exp. for defeating the Dream Cloud.

One case where this can be a little more complicated is the use of abilities. Say Poco is level 2, Arc is level 3, and Kukuru is level 1. Poco uses the Battle Drum ability and affects all three characters. He would gain 6 exp. for the use of the ability (the sum of the levels of all those affected, 2+3+1), and one additional Experience Point for being the target of the ability. (Character level divided by 3, round fractions up.) Therefore, Poco would recieve 7 experience total.

Obviously, you recieve much more experience for defeating enemies than for any other action, so if one of your characters is lagging behind in level and not really able to contribute effectively to the group, let them get the finishing blow on enemies, and they should level up nicely.