The six ability scores are named: strength, intelligence, wisdom, dexterity, constitution, and charisma, as in pretty much every version of the game. Here we also come to a departure in the philosophy between OD&D and AD&D. AD&D characters are supposed to be above average, and it's recommended that a character have at least two scores of 15+ to ensure survival. I'm somewhat taken aback that there's no method given for determining ability scores: players are referred to the Dungeon Masters Guide, a book that won't be released for two years after this. It's said that the scores range between 3 and 18, but for anyone trying to learn the game from the PHB, the method of getting those numbers is a mystery.
The ability is briefly outlined as a measure of muscle and endurance, and then an example Is given to relate the ability to the real world: as a rule of thumb, a character can lift their strength score times ten in pounds over his head (so a character with strength 3 can do a military press of 30 pounds, and one with strength 18 can press 180). (As far as I can tell, this is the first time these values are given in D&D). I tried to look up the world record for a military press, but wasn't able to find anything official. I was getting figures of 400+ pounds, and some over 500, so Gary is very far away from reality on this one (unless exceptional Strength scales this figure up very quickly).
Strength remains the prime requisite for Fighters, as in OD&D. This means that a fighter with a high strength score earns more experience points. In AD&D, you get a 10% XP bonus for a Strength of 16+. This is a change from OD&D, where the 10% bonus came with a score of 15+, and you could also get a 5% bonus from a score of 13 or 14. It also looks as though they've done away with XP penalties for having a low prime requisite.
Indeed, it may not even be possible to have a low prime requisite. Next to the write-up for Strength is a table that shows what classes and races you can choose based on your strength. To be a fighter you need a strength of at least 9, so the XP penalty is moot. Aside from the race and class restrictions, there are also upper limits noted for female characters. As I've mentioned before, it's a realistic inclusion, but I still don't like the idea of penalising female PCs just because they're female.
Any fighter with a strength of 18 can also roll percentile dice to determine exceptional strength (resulting in scores such as 18/54 or 18/98). A high roll here can net the fighter (and only the fighter) some hefty combat bonuses. There's a table below that shows combat bonuses and penalties based on your strength score. In general, characters have actually been weakened here when compared to OD&D; the penalties for having a low score have increased, and the bonuses come later and don't advance as high.
There are also some bonuses and penalties for non-combat activities, such as carrying capacity, and opening doors. Characters in OD&D were better at opening doors than their AD&D equivalents, but the increase in carrying capacity for a high score in AD&D is far higher than it used to be. An OD&D character with the highest strength had a bonus of +1200, whereas an AD&D character with the same score gets a bonus of 3000. I thought perhaps that the games used different units of weight, but it seems that both measure weight in coins.
A new addition is the ability to Bend Bars or Lift Gates, such as a portcullis. This is given as a percentage chance, but each can be attempted but once on a particular gate or bar. So if you fail to lift a portcullis you can't try again, but you can still make one attempt to bend the bars and squeeze past.