Outside of thieves’ skills and some info about tracking, AD&D 1st edition did not have many details about skills (later called non-weapon proficiencies). However, the Dungeon Master’s Guide listed a few professions as “secondary skills” and topics of lore to be mastered by sages.
AD&D 1e Oriental Adventures (1985) and AD&D 2e (1989) Rule
Proficiency Checks: Roll 1d20. If equal or less than ability score, action succeeds. If over, action fails.
Check Modifiers…
* Very easy proficiency … +3 to ability score
* Easy proficiency … +1 to ability score
* Normal proficiency … no modifier
* Hard proficiency … -1 to ability score
* Very hard proficiency … -2 to ability score
* Extremely hard proficiency … -3 to ability score
HOUSE RULE: Players may pick one of the following topics that a character may have specific background in studying. Whenever an Intelligence task involves that topic, the character gains a +5 bonus on the ability check roll.
* Profession: Alchemist
* Profession: Armorer
* Profession: Blacksmith
* Profession: Forester
* Profession: Gambler
* Profession: Hunter/Fisher (hook and line)
* Profession: Husbandman (animal husbandry)
* Profession: Jeweler/Lapidary
* Profession: Leather worker/Tanner
* Profession: Limner/Painter
* Profession: Mason/Carpenter
* Profession: Miner
* Profession: Musician/Performer
* Profession: Navigator (fresh or salt water)
* Profession: Sailor (fresh or salt)
* Profession: Shipwright (boats or ships)
* Profession: Tailor/Weaver
* Profession: Teamster/Freighter
* Profession: Trader/Barterer
* Profession: Trapper/Furrier
* Profession: Woodworker/Cabinetmaker
* Humankind: Art & Music
* Humankind: Biology
* Humankind: Demography
* Humankind: History
* Humankind: Languages
* Humankind: Legends & Folklore
* Humankind: Law & Customs
* Humankind: Philosophy & Ethics
* Humankind: Politics & Genealogy
* Humankind: Psychology
* Humankind: Sociology
* Humankind: Theology & Myth
* Demi-Humankind: Art & Music
* Demi-Humankind: Biology
* Demi-Humankind: Demography
* Demi-Humankind: History
* Demi-Humankind: Languages
* Demi-Humankind: Legends & Folklore
* Demi-Humankind: Law & Customs
* Demi-Humankind: Philosophy & Ethics
* Demi-Humankind: Politics & Genealogy
* Demi-Humankind: Psychology
* Demi-Humankind: Sociology
* Demi-Humankind: Theology & Myth
* Humanoid/Giantkind: Biology
* Humanoid/Giantkind: Demography
* Humanoid/Giantkind: History
* Humanoid/Giantkind: Languages
* Humanoid/Giantkind: Legends & Folklore
* Humanoid/Giantkind: Low & Customs
* Humanoid/Giantkind: Sociology
* Humanoid/Giantkind: Theology & Myth
* Science: Architecture & Engineering
* Science: Astronomy
* Science: Chemistry
* Science: Geography
* Science: Geology & Mineralogy
* Science: Mathematics
* Science: Meteorology & Climatology
* Science: Oceanography
* Science: Physics
* Science: Topography & Cartography
* Fauna: Amphibians
* Fauna: Arachnids
* Fauna: Avians
* Fauna: Cephalopods & Echinoderms
* Fauna: Crustaceans & Mollusks
* Fauna: lchthyoids
* Fauna: Insects
* Fauna: Mammals
* Fauna: Marsupials
* Fauna: Reptiles
* Flora: Bushes & Shrubs
* Flora: Flowers
* Flora: Fungi
* Flora: Grasses & Grains
* Flora: Herbs
* Flora: Mosses & Ferns
* Flora: Trees
* Flora: Weeds
* Arcana: Astrology & Numerology
* Arcana: Cryptography
* Arcana: Divination
* Arcana: Dweomercraft (study of magical items)
* Arcana: Heraldry, Signs & Sigils
* Arcana: Medicine
* Arcana: Metaphysics
* Arcana: Planes (Astral, Elemental & Ethereal)
* Arcana: Planes (Outer)
* Arcana: Enchantments (magic affecting emotions)
* Arcana: Necromancy (magic affecting the dead or undead)
* Arcana: Evocation (magic affecting primal elements – fire, water, earth, air, etc.)
* Arcana: Transmutation (magic affecting polymorph spells or shapechangers)