The Complete Bard's Handbook[]
Acting enables a character to skillfully portray various roles. Acting is most often used as a form of entertainment; it can also be useful in aiding a disguise. If both acting and disguise are known, the proficiency check for either is made with a +1 bonus.
Proficiency checks are required only if the actor must portray a particularly difficult character or is attempting an "ad lib" role (i.e., a nonrehearsed role or on short notice).
The Complete Book of Humanoids[]
This proficiency allows a character to skillfully portray various roles, often as an entertainment. It can also be used to enhance a disguise. If a character has both acting and disguise proficiencies, the check for either is made with a +1 bonus.
Proficiency checks are required only if the actor must portray a particularly difficult role or is attempting to "ad lib" without rehearsal.
The Complete Ninja's Handbook[]
Acting: This proficiency, originally presented in The Complete Bard's Handbook, allows a character to skillfully portray another person. Although acting is usually considered a form of entertainment, it can be useful in helping the ninja accomplish mission goals. If the ninja has both the Acting and Disguise proficiencies, the proficiency check for either is made with a +1 bonus.
Proficiency checks for Acting are required only if the actor must portray a particularly difficult character or is attempting to ad lib a role (a nonrehearsed role or a performance on short notice).