(Garou-only) Each point of Past Life represents one strong connection to a direct ancestor. Per point of Past Life, a Garou has a 20% chance of tapping into his ancestral memories and gaining an extra die roll for one skill for the duration of a scene.
Example: Bob has never fought with a klaive before, having only hand-to-hand brawling experience and Past Life:3. He hopes to glean some insight from his past lives and rolls 3 dice at diff:8, spending a point of Willpower. He gets two successes and suddenly has a respectable knowledge of how to use a klaive--for that one scene. The Past Life background can only be tapped like this once per day.
The Past Life background cannot be used to learn new gifts or rites or come up with esoteric knowledge, and characters with high levels of Past Life occasionally get "possessed" or talk with themselves--which can be humorous or dangerous depending on the situation. Garou with a high Past Life background value are generally looked upon as being a bit crazy.