Rules reference
Advancement in Call of Cthulhu 7th Edition
How progression works and how to track it. Call of Cthulhu 7th Edition is a horror investigation roleplaying game based on H.P. Lovecraft's Cthulhu Mythos. Players take on the roles of Investigators, ordinary people who uncover cosmic horrors beyond human comprehension. As you investigate mysteries, your character's Sanity slowly erodes, skills improve through use, and the line between reality and madness blurs.
Key points
Call of Cthulhu advancement is a loop: use skills → mark them → roll to improve after sessions.
- Percentile skill system: Roll d100, succeed if equal to or below skill rating
- 8 Characteristics: STR, CON, POW, DEX, APP, SIZ, INT, EDU (plus Luck)
- Occupation system: Each occupation grants skill bonuses and Credit Rating range
- Sanity mechanics: Starts at POW, maximum reduced by Cthulhu Mythos exposure
- Skill improvement: Mark skills during play, improve after sessions
- Luck: Spend after a roll, point for point, to turn a failure into a success; can't be used on Sanity, damage, Luck rolls, or pushed rolls
Call of Cthulhu progression: mark skills you used successfully during play, then roll improvement checks between sessions.
- During play: when you succeed at a skill roll, mark that skill for improvement.
- Between sessions (or at a natural break): roll improvement checks for marked skills.
- Improvement check: roll d100; if you roll OVER your current skill, gain 1d10 percentiles.
- Higher skills are harder to improve (diminishing returns are built in).
- Sanity can be recovered through successful therapy or long-term downtime.
After the session, roll to improve the skills you actually used. Your investigator gets better where the story pushed them.
Progress isn’t only skills: track Sanity consequences and long-term effects as part of the campaign’s arc.
- Mistake: XP drift (nobody remembers what changed). Fix: Record gains/spends right after sessions and keep a short history.
- Mistake: Buying upgrades that don’t show up in play. Fix: Spend toward your concept and the scenes you actually get.