Unlike other games, Call of Cthulhu uses a different form of advancement.

Upon Completing a segment of the game (Generally major Investigation points) Investigators are granted the chance to increase any skills they successfully used in their investigation.

Any successful skill used by your the game, should bet checked with the used tag on your character sheet for this purpose. Upon Completing a segment, You are then allowed to roll against your skill. a successful roll above your current skill value increases that skill by 1d3 points, to a maximum of 99% (The better you are at a skill the harder it is to improve it.)

Also at the End of each Segment, Players regain a Dice amount of Sanity based on their performance during the investigation.

(1d2,1d3,1d4,1d6,1d8 or 1d10)

Any skill raised above 90% also increases your Sanity by 1d4 points
(this only occurs once per skill!)