Sims 3: How to Install Mods and Set Up the Mods Folder

The Sims 3 Mods folder goes in Documents\Electronic Arts\The Sims 3\Mods, and you have to create it yourself: put a Resource.cfg file directly inside it, create a Packages folder next to that file, and drop your .package mod files into Mods\Packages. The game will not load anything from that folder without Resource.cfg, which is the step most failed installs miss, and the “Mods folder download” many mod sites offer is simply a ready-made copy of that same structure. This guide covers the folder paths for Windows and Mac, what goes in Resource.cfg, the difference between .package and .sims3pack files, the cache files to delete, and how to troubleshoot mods that do not show up.

Where the Sims 3 User Folder Is

The Sims 3 keeps saves, settings and mods in your user Documents folder, not where the game is installed. That is true whether you bought it on Steam, the EA app, or an old disc:

• Windows: Documents\Electronic Arts\The Sims 3
• Mac: Documents/Electronic Arts/The Sims 3

The folder is created the first time the game runs, so launch The Sims 3 to the main menu once, quit, then go looking. On Windows 11, Documents is often redirected into OneDrive (OneDrive\Documents). If you cannot find the folder, check there; the game uses whichever Documents location Windows reports, and a common trap is ending up with two copies of the folder and editing the one the game does not read.

Step by Step: Set Up the Mods Folder

1. Open Documents\Electronic Arts\The Sims 3.
2. Create a new folder named Mods (capital M, no spaces).
3. Inside Mods, create a folder named Packages. Many setups also add an Overrides folder for mods that replace default game files.
4. Place a file named Resource.cfg directly inside Mods, next to Packages, not inside it.
5. Put your .package mod files in Mods\Packages. You can sort them into subfolders there.

The finished structure looks like this:

Documents\Electronic Arts\The Sims 3\     Mods\         Resource.cfg         Packages\             (your .package files and subfolders)         Overrides\   (optional) 

What Resource.cfg Does

Resource.cfg is a small text file that tells the game which folders to scan for mods. Without it, the Mods folder is ignored entirely. You can unzip one of those ready-made “framework” downloads into The Sims 3 folder, or make the file yourself: create a plain text file, paste in the lines below, and save it as Resource.cfg (make sure Windows has not added a hidden .txt on the end).

Priority 500 PackedFile Packages/*.package PackedFile Packages/*/*.package PackedFile Packages/*/*/*.package PackedFile Packages/*/*/*/*.package PackedFile Packages/*/*/*/*/*.package 

Each PackedFile line reads one more level of subfolders, which is why the common version reaches five folders deep. A mod buried deeper than the file allows will simply not load. Setups with an Overrides folder add a second block with a higher priority number pointing at Overrides/*.package, so replacement files win over everything else.

.package vs .sims3pack Files

Sims 3 custom content comes in two formats, and they install differently:

• .package files go in Mods\Packages. This is the format for gameplay mods, script mods and most custom content. If a download arrives as a .zip, .rar or .7z, extract it first; the game cannot read archives.
• .sims3pack files are installed through The Sims 3 Launcher (the window that opens before the game), not the Mods folder. Double-click the file or use the Launcher’s Downloads section to install it. They end up in the game’s own content database rather than as loose files you can easily sort or remove.

Script mods (the type that changes game behavior, such as story progression or master control mods) also go in Mods\Packages, but they are built against a specific game version, so download the build a mod lists for your version. The Sims 3 has not been patched in years; per long-standing player reports the Steam release sits on patch 1.67 and the EA app release on 1.69, and the major script mods publish builds for both.

Clear the Cache After Every Change

The Sims 3 builds cache files that remember old content. After adding or removing mods, close the game and delete these files from Documents\Electronic Arts\The Sims 3 (the game rebuilds them on launch):

• CASPartCache.package
• compositorCache.package
• scriptCache.package
• simCompositorCache.package
• socialCache.package

Players on EA’s official forums single out scriptCache.package as the one that matters most for mods, but clearing all five is the standard routine. Many players also empty the WorldCaches folder. Never delete your Saves folder.

Troubleshooting Mods That Do Not Work

• Nothing loads at all: Resource.cfg is missing, in the wrong folder, or saved as Resource.cfg.txt.
• Some mods load, others do not: the missing ones are nested deeper than Resource.cfg reads, or they are still zipped.
• Game crashes or behaves oddly after installing: remove mods in halves until the problem goes away to find the culprit, and clear the cache each time. Two mods that change the same thing will conflict.
• A Sim is stuck after a mod change: our Sims 3 reset guide covers the built-in fix.

Always back up your Saves folder before adding big gameplay mods. Once your setup works, our list of the best Sims 3 mods is a good place to start. Playing other generations too? The process is different in our Sims 2 mods guide and Sims 4 mods guide, and every other Sims walkthrough is on our Sims guides hub.

Frequently Asked Questions

Where is the Mods folder in The Sims 3? It does not exist until you create it. Make it at Documents\Electronic Arts\The Sims 3\Mods, with a Packages folder inside.

Do I need Resource.cfg for Sims 3 mods? Yes. Without a Resource.cfg file directly inside the Mods folder, the game ignores every mod in it.

Why are my Sims 3 mods not showing up? The usual causes are a missing or misnamed Resource.cfg, mods still inside a .zip file, mods nested too many subfolders deep, or stale cache files. Delete the five cache files and restart.

Do Sims 3 mods work on the Steam and EA app versions? Yes. Both use the same Documents\Electronic Arts\The Sims 3 folder. The two stores are on slightly different final patches, so pick the script mod build that matches yours.

Where do .sims3pack files go? Not in the Mods folder. Install them through The Sims 3 Launcher, which handles that format.