Movan said: If it's an ability check where you don't get to add your proficiency bonus, then Jack of All Trades let's you add 1/2 (rounded down) of your proficiency bonus to that number. (I started to write an example, looked up "ability checks" in the PHB index, did some reading and now I'm confused, haha!) What is an ability check? Isn't it any roll relating to an ability? And since 5e is now all ability-based, the rule might be interpreted as "any roll" for a bard gets either proficiency (if she has it), or 1/2 of any roll in an ability which the bard lacks proficiency as per Jack of All Trades. 1. Examples? A bard picks up a warhammer and swings it at a skeleton. Normally, characters who lack proficiency in that weapon wouldn't get to add any proficiency bonus, but does the bard get 1/2 proficiency bonus rounded down? If not, why not? Attacks are now an "ability check", right? 2. Another example, and this one is less ambiguous I think: A bard tries to use Deception skill vs. a city guard. He's not proficient in that skill, but Jack of All Trades lets him add 1/2 his proficiency bonus (rounded down). Let me know what you guys think. I numbered Movan's quote above for reference. 1. The attack requires an attack roll to succeed not an ability check. Even though the mechanics are basically the same, the only difference being the check needs to beat a DC and the attack needs to beat an AC, they are technically different. Just like a Dexterity Check is different from a Dexterity Save, where a PC might get proficiency in the save but not the check although the mechanics are the same. 2. Yes, in this example Jack of All Trades would apply. Skills are sort of a subset of abilities that grant proficiency with certain types of ability checks. That is why you will see official products list the use of skills as make a Wisdom (Perception) Check" or "Charisma (Deception) check. Skill checks are a focused form of an ability check. To me the key is how it is written in the rules. If the word check is used it is intended as an ability check, if the word save is used it is intended as an ability save, etc. Hope this helps :-)