How to Install Mods on Sims 3: Package and Sims3Pack

Q: Where do I put mods in Sims 3?

.package files go in Documents\Electronic Arts\The Sims 3\Mods\Packages . .sims3pack files are installed through the launcher, which reads them from the Downloads folder in the same place.

First check the file type

Sims 3 downloads come in two formats, and each one installs a different way.

File	What it usually is	Where it goes	How to remove it
`.package`	Script mods such as NRaas, tuning mods, default replacements, most CC	`Documents\Electronic Arts\The Sims 3\Mods\Packages`	Delete the file
`.sims3pack`	Clothes, objects, lots, Sims and worlds made for the launcher	`Documents\Electronic Arts\The Sims 3\Downloads`, then installed by the launcher	Uninstall it in the launcher's Installed Content tab
`.zip`, `.rar`, `.7z`	An archive that holds one of the two above	Nowhere. Extract it first

The game cannot read archives. If a mod still does nothing after you copied it in, check that you copied the file from inside the archive and not the archive itself.

Install a .package mod

Close the game and the launcher.
Open Documents\Electronic Arts\The Sims 3. This is the folder with your Saves, not the install folder in Program Files.
If there is no Mods folder yet, set it up once: a Mods folder holding a Packages folder, an Overrides folder and a Resource.cfg file. The Mods folder page has the exact file contents and two ready-made downloads.
Extract the download and copy only the .package file into Mods\Packages. Subfolders such as Packages\NRaas are fine.
Delete the cache files listed below.
Start the game. NRaas says a pop-up lists the script mods it loaded. Tuning mods, sliders, skins, clothes and objects never appear in that list, so check those in the game itself.

Use Overrides only when a creator tells you to. NRaas's install page says every other .package belongs in Packages. Never keep two copies of the same mod: NRaas warns the result is unpredictable.

Install a .sims3pack file

Double-click the .sims3pack file. The launcher opens and installs it. You can also copy the file into Documents\Electronic Arts\The Sims 3\Downloads and install it from the launcher's Downloads tab.
Check the launcher's Installed Content tab. If Run without custom content is ticked there, untick it, or nothing you installed will load.
Start the game.

Launcher content is stored in the DCCache folder, so do not empty that folder when you clean caches. To look inside a .sims3pack before installing it, CUSTARD on Mod The Sims opens the file and flags corrupted items. Script mods are never .sims3pack files.

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Delete the caches every time

With the game closed, delete these files in Documents\Electronic Arts\The Sims 3. EA Help says they are safe to remove and the game makes them again.

CASPartCache.package
compositorCache.package
scriptCache.package
simCompositorCache.package
socialCache.package, if you have Showtime (NRaas lists this one)

If something still looks wrong, EA Help's next step is to delete the files inside Thumbnails, then the files inside WorldCaches.

EA app, Steam and Mac

Version	What changes
EA app (Windows)	Nothing in the steps above. The Mods folder is in Documents for every Windows version
Steam	Same Mods folder. Only engine patches differ: files such as `Sims3SettingsSetter.asi` go in `Steam\steamapps\common\The Sims 3\Game\Bin`
Mac	Same layout in `/Users/<username>/Documents/Electronic Arts/The Sims 3/Mods`. From macOS 10.15, EA says only the 64-bit version runs, and it installs as a separate game in the EA app

Script mods are built for a game patch. NRaas labels each download with the patches it supports (1.67, 1.69 and 1.70 on its mod list), and other creators publish separate files per patch. Check your patch number before you download. EA suggests players on 1.67 or earlier update to 1.69. The NRaas page shows which mods to start with.

Mods not showing up? Check these

Symptom	Likely cause and fix
No mod loads at all	`Resource.cfg` is missing, sits in the wrong folder, or is really named `Resource.cfg.txt`. It must be directly in `Mods`
One mod is missing	The file is in `Mods` and not `Mods\Packages`, it is still zipped, or it was made for another patch
NRaas menu options are missing	NRaas says this is nearly always a bad install: an outdated script mod, a duplicate, or an old Mods folder left inside the game's install directory
Launcher content is missing	Untick Run without custom content in the launcher
Game crashes while loading	EA Help: run without custom content once. If the game loads, add your content back a little at a time to find the bad item
Launcher says the version is incompatible	Delete `Version.tag` in `Documents\Electronic Arts\The Sims 3`

The main Sims 3 mods page has a symptom picker for crashes, lag and Error 12.

FAQ

Where do I put mods in Sims 3?

.package files go in Documents\Electronic Arts\The Sims 3\Mods\Packages. .sims3pack files are installed through the launcher, which reads them from the Downloads folder in the same place.

Do I have to turn mods on in the game options?

No. The setup guides from Mod The Sims and NRaas need no in-game setting: a correct Mods folder with Resource.cfg is enough. The one switch to check is Run without custom content in the launcher, which must stay unticked.

Can I install Sims 3 mods on a Mac?

Yes. The folder layout is the same under Documents/Electronic Arts/The Sims 3. The engine patches named on this site are Windows files.

Do Sims 4 mods work in The Sims 3?

No. Sims 2 and Sims 4 also use .package files, but the game cannot use them, and a wrong-game file in your Mods folder can cause trouble. Remove them.