How to change the Sims 4 CAS background

Download a CAS background mod, put its .package file in your Mods folder, and restart the game. The new background replaces the default Create a Sim background. Keep only one CAS background in the Mods folder.

The game has no menu to pick a CAS background. A CAS background mod is an override. It replaces the game’s own background file. MustHaveMods says: “Once installed, you don’t need to enable or select them in-game.”

This is the LifeSim blog. We make a different life sim game. We opened every source on this page on November 11, 2026. Mods change after game updates, so read the creator’s page before you install.

Steps to install a CAS background

1. Download the background from the creator’s page. Read the notes on that page.
2. If the file is a .zip or .rar file, extract it. You need the .package file.
3. Move the .package file into Documents / Electronic Arts / The Sims 4 / Mods. If there is no Mods folder, make one.
4. Remove any other CAS background from the Mods folder.
5. Delete the file localthumbcache.package in the The Sims 4 folder.
6. Start the game. Open Game Options, then Other.
7. Make sure that Enable Custom Content and Mods is on. Then restart the game.
8. Open Create a Sim and look at the background.

The EA help page gives the same Game Options steps for all mods. MustHaveMods says to keep the file “no more than one folder deep inside Mods.” A subfolder such as Mods / Backgrounds is OK.

Do I need to turn on script mods?

No. A CAS background is a .package file with images and no script. MustHaveMods says that Script Mods Allowed “isn’t required for visual overrides.” You only need Enable Custom Content and Mods.

New to the Mods folder? Read our beginner’s guide to Sims 4 mods first. It explains the difference between mods and custom content.

Each CAS background replaces the same game file. The game can use only one version of that file. When two mods replace it, they conflict.

MustHaveMods says that “you can only use ONE CAS background at a time.” It says that two or more can make the default background come back, or can break the CAS room. SimsCommunity also says that the backgrounds replace the default, so only one can work.

Creators give the same warning. Yosarna offers Basic CAS Backgrounds in six colors on ModTheSims. The page tells you to use only one of them and to replace any CAS package that you already have.

How do I switch between backgrounds?

• Make a folder outside the Mods folder, for example on the desktop.
• Keep the backgrounds that you do not use in that folder.
• Move one background into Mods when you want it.
• Delete localthumbcache.package each time that you switch.

A mod manager can also turn files on and off. Our Sims 4 mod manager guide compares the tools.

Does the same rule apply to other overrides?

Yes. MustHaveMods says to use only one of each type: one CAS background, one loading screen, and one main menu override. You can have one of each type at the same time.

Usually, the cache still shows the old background, or a second background is in the Mods folder. Delete localthumbcache.package, remove the other backgrounds, and restart the game.

The file localthumbcache.package is in Documents / Electronic Arts / The Sims 4. It is a cache file, not a mod. MustHaveMods also says to delete avatarcache.package if you have it.

Why do some backgrounds need other files?

Some creators build a background with other custom content. Basic CAS Backgrounds by Yosarna needs a rug by Mixed’up and recolors by Raemia. Without them, the background does not show correctly. Our guide to Sims 4 CC explains how to install that type of file.

Does a game update break CAS backgrounds?

Not often. MustHaveMods says that CAS backgrounds “rarely break during game updates.” If CAS shows errors or stops loading after an update, another mod can be the cause. Our Better Exceptions guide shows how to find the mod that causes an error.

How do I test if a mod causes the problem?

1. Close the game.
2. Move the whole Mods folder to the desktop.
3. Delete localthumbcache.package.
4. Start the game and open Create a Sim.

If the default background comes back, a file in your Mods folder caused the problem. Move the files back in small groups to find it.

Find them on ModTheSims and CurseForge, or on the creator’s own Patreon, Tumblr, or website. Download only from the creator’s own page or from a large mod site.

EA does not check mods. The EA help page says that “Maxis and EA don’t pre-screen, endorse, or support specific Mods or Custom Content.” It tells players to download only from “a trusted source or creator.”

Examples that we opened today

The ModTheSims page of the TS2 inspired background showed more than 29,000 downloads today. A list on SimsCommunity from December 2022 shows more creators, such as Annett, KatVerse, and mosaica. It links to sites such as The Sims Resource, Patreon, and Tumblr.

What is a CAS mirror background?

It is a CAS background with a mirror in it. MustHaveMods says that it “lets you view the back of your Sim’s outfit.” Some mirror backgrounds need other mods or settings, so read the creator’s notes.

Want more ideas for your game? See our list of the best Sims 4 mods.

No. The Sims 4 has no in-game setting for the CAS background. On PlayStation and Xbox, you cannot add mods, so you cannot change it.

The EA help page says: “Mods are only available for PC and Mac players; they can’t be downloaded on PlayStation® or Xbox.” MustHaveMods also says that changing the CAS background requires a PC or a Mac.

Can you change the main menu background on console?

Yes, with a game feature. The console update of October 31, 2018 added it. The patch notes say: “press Left or Right on the Right Stick to cycle through the backgrounds.” You can pick a background from the base game and from some packs that you have.

The notes say that your choice stays the next time that you go to the main menu. This feature is for the main menu only, not for CAS. Our Sims 4 console vs PC comparison lists other differences.

What can you change in CAS without mods?

You can change the Sims themselves. To open CAS for a Sim in a save, read how to edit a Sim in The Sims 4. For game codes, see our Sims 4 cheats list.

Use the same method as for a CAS background. Put one loading screen override or one main menu override in Mods. Then delete the cache and restart the game.

Sims 4 loading screen mods

Plumbob Portraits by batuusims on CurseForge has two loading screens, based on the box art of The Sims 3. The page says: “you can only have one loading screen override installed at a time.” Extract the file, put it in Mods, and turn on Enable Custom Content and Mods.

Sims 4 main menu mods

Enchanted Grove Main Menu on CurseForge shows a glowing tree. Its page says: “ONLY INSTALL 1 MAIN MENU OVERRIDE.” If a download has more than one version, such as static and animated, install only one.

Snooty Sims lists more main menu mods. One set, Soft Florals, also replaces the loading screen and the CAS background. If you use a set like this, remove your other overrides of those types.

MustHaveMods says that main menu overrides break more often after big game updates. If the main menu looks wrong after an update, remove the override.

Yes. LifeSim is our game. It is free, with no ads, no subscription, and nothing to buy. You play it in a web browser at play.lifesim.com or in the iPhone app.

In LifeSim, you live one life, day by day, in a real city on a 3D map of Earth. People talk back in their own words and remember you. Read how to play LifeSim to start.

LifeSim does not fit you if you want to dress Sims in CAS, use custom content, or change backgrounds. It has no Mods folder. Stay with The Sims 4 for those things.

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• MustHaveMods: How to change Sims 4 CAS backgrounds and menu overrides (January 18, 2026)
• EA Help: How to install Mods in The Sims 4
• SimsCommunity: The Sims 4 CAS backgrounds (December 29, 2022)
• ModTheSims: Basic CAS Backgrounds by Yosarna
• ModTheSims: TS2 inspired CAS background for The Sims 4 by thorben.maerz
• ModTheSims: CAS background light grey by Senni (February 12, 2023)
• CurseForge: TS2 Inspired CAS Background Room by simsi_45
• CurseForge: Plumbob Portraits, Loading Screen Override by batuusims
• CurseForge: Enchanted Grove Main Menu (November 4, 2025)
• Snooty Sims: New main menu mods (January 19, 2025)
• SimsCommunity: The Sims 4 console update and patch notes (October 31, 2018)