I run a campaign where one of my players, a 5th level Gloom Stalker ranger, wants to multiclass into a rogue at 6th level. He’s already proficient with Thieves’ Tools due to his background. When he takes his first level of rogue, does he get expertise in Thieves’ Tools now? Can he choose another tool proficiency or another skill instead? The multiclassing section in the PHB doesn’t really address it, so any advice would be appreciated!

When you go into character settings the selection under {edit: background tool} should now be blank-they should be able to pick something else

Thanks for the reply, HeathSmith. I’ll ask my player to check it out.

If you already have proficiency in something when you multiclass you don't get expertise and you don't get proficiency in something else. Since he's multiclassing into Rogue he can choose one of his two expertises he gets at first level to be expertise in Theives' tools. He doesn't gain any benefits from already being proficient with Thieves' Tools.

I'm actually pretty sure the Players hand book states that if you multiclass or pick a background and end up getting 2 of the same proficiency, you can choose a new tool or language proficiency that makes sense. 

Quote from Lostwhilefishing >>

If you already have proficiency in something when you multiclass you don't get expertise and you don't get proficiency in something else. Since he's multiclassing into Rogue he can choose one of his two expertises he gets at first level to be expertise in Theives' tools. He doesn't gain any benefits from already being proficient with Thieves' Tools.

try the scenario in DDB and see how it works for you...when you add rogue and then look at the background tab, what was thieves' tools (never a dropdown) is now a dropdown allowing you to select any other tool.

and on liger's comment under Backgrounds: "If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead. "

and when you look at Multiclassing proficiencies:

That is the case for when you're starting out. Essentially you get your background proficiencies and your starting class proficiencies at the same time and a feature of background options is that if you already have that option you can pick others. This ensures that people start out with a set number of proficiencies and aren't penalized for picking stuff that overlaps thematically.

As for multiclassing later on, that's a different situation. In this case I would not allow someone to gain any tool proficiency by becoming a rogue. They grant proficiency with thieves' tools because they are thieves. If you already have it, you don't get another bonus just like you don't get your pick of armor proficiencies because you already had light armor.

Quote from ligerdrag20 >>

I'm actually pretty sure the Players hand book states that if you multiclass or pick a background and end up getting 2 of the same proficiency, you can choose a new tool or language proficiency that makes sense. 

 No, that is completely wrong. It's only at character creation and if you gain the same proficiency from your starting class and your background you can choose a different proficiency. For example, being a Rogue with the Urchin background. 

I'm actually pretty sure the Players hand book states that if you multiclass or pick a background and end up getting 2 of the same proficiency, you can choose a new tool or language proficiency that makes sense. 

Although that sounds reasonable, I could not find anywhere in the multiclassing rules of PHB nor anything anywhere else to support this as RAW.

Quote from BioWizard >>

 

Although that sounds reasonable, I could not find anywhere in the multiclassing rules of PHB nor anything anywhere else to support this as RAW.

its specific to the OP's example because the rogue is the only class where you get a specific tool proficiency when you add it as a multiclass and in his case, he already had thieves tools from the background.  So then you look at the background rule -> "If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead. " (note there's no limiter that says this only applies during character creation)

...which is also how it works mechanically on DDB.  When you add the rogue class to an existing character with say a Criminal background, the thieves tool unlocks in the background section and you can then pick any tool.

Quote from HeathSmith >>

Quote from BioWizard >>

 

Although that sounds reasonable, I could not find anywhere in the multiclassing rules of PHB nor anything anywhere else to support this as RAW.

its specific to the OP's example because the rogue is the only class where you get a specific tool proficiency when you add it as a multiclass and in his case, he already had thieves tools from the background.  So then you look at the background rule -> "If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead. " (note there's no limiter that says this only applies during character creation)

...which is also how it works mechanically on DDB.  When you add the rogue class to an existing character with say a Criminal background, the thieves tool unlocks in the background section and you can then pick any tool.

What limits it to character creation is that, as you yourself say, it’s a background rule, and you can’t add a background after character creation.

If you already have thieves tools proficiency, nothing happens when you multiclass into rogue, just like how if you already have light armor proficiency, nothing happens.

Quote from HeathSmith >>

Quote from BioWizard >>

 

Although that sounds reasonable, I could not find anywhere in the multiclassing rules of PHB nor anything anywhere else to support this as RAW.

its specific to the OP's example because the rogue is the only class where you get a specific tool proficiency when you add it as a multiclass and in his case, he already had thieves tools from the background.  So then you look at the background rule -> "If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead. " (note there's no limiter that says this only applies during character creation)

...which is also how it works mechanically on DDB.  When you add the rogue class to an existing character with say a Criminal background, the thieves tool unlocks in the background section and you can then pick any tool.

 Well, yes there is. Since it's in the chapter on "Backgrounds" and the chapter on Multiclassing says nothing of the sorts. As for using DDB, it's not really a valid source of information. Never mind the fact that it might have bugs in it and allows for homebrews, it's also basically just virtual notepad. Sure, you can write down pretty much whatever you want on it, but that doesn't make it true, if you catch my drift?

i do get that DDB is not a source, but its also a for-profit organization with a mission to program rules as-is without interpretation so its a decent sounding board for mechanics...BUT

you all win....i eat all my words and say i'm wrong .....see red, which, as far as I can tell, doesn't seem to appear anywhere else - including the PHB errata (which i'd say suggests how the rules were intended in the 1st two docs)

From PHB: If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead.

From Basic Rules: If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead.

From D&D Essentials Rulebook: If a 1st-level character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead.

______

but having said all that, i'd still let them pick another proficiency with the idea that, while learning to be a rogue, they didn't just twiddle their thumbs because they already knew thieves tools - they took that time to learn something else. 

i'd also like to point out that backgrounds can be edited in AL - specifically the background feature...also understanding that AL < source books - but the idea that you can edit backgrounds post-creation is out there.

Thanks, everyone,  for all of your replies - I very much appreciate everyone's input. I've decided to allow him a second tool proficiency (he took tinker's tools) as it feels more like a flavor option. @HeathSmith, I do agree with you that it does seem like more of a background related issue, so RAW probably doesn't allow it, but I am feeling like a kindly DM and don't feel like it will give him some sort of unfair advantage. We shall see how it goes. Of course, they might not survive tonight's session, so it might all be academic. ;-)

As a DM if a character got a 2nd copy of a proficiency, whatever RAW says, I'd let him or her pick a new proficiency.

Quote from BioWizard >>

As a DM if a character got a 2nd copy of a proficiency, whatever RAW says, I'd let him or her pick a new proficiency.

Wow, martial class Mountain Dwarves are the new skill monkeys.