I've noticed some traffic of people wondering how to install OptiFine into Hexxit on a Mac, and tutorials only cover this on the Windows operating system. The below tutorial will explain (in the best of my ability) how to install OptiFine into Hexxit. Requirements: 1. The correct OptiFine version matching that of the current Hexxit version. 2. The current Hexxit version. Instructions: 1. First, open a Finder window and go to the top of the screen. Find 'Go' at the top of the screen, and click on it. Click on the option that is second from the bottom. Paste this in (without the quotes): '/Users/<UserName>/Library/Application\ Support/technic/hexxit/bin' - Where <UserName> is your username, and press 'Go'. Keep this window open. 2. Now, find your Optifine zip file (where ever you put it). Double click this file to extract it. 3. Go back to the Finder window you opened previously (the one that contains 'bin', and other folders). Find 'bin' and open it. Now find 'modpack.jar' (it is the second one from the bottom). Rename this file 'modpack.zip'. Make sure that it isn't 'modpack.zip.jar' or something similar. The icon should change when this happens. 4. Double click 'modpack.zip' to extract it. 5. Open up your Optifine folder (not zip) and your modpack folder (not zip). Put these side-by-side. Hold down 'command' and press 'a' at the same time (with the Optifine folder selected) to select every file in the Optifine folder. It should look a little like this: 6. With the Optifine folder still selected, press 'command' and 'c' at the same time. Click on the 'modpack' folder and press 'command' and 'v' at the same time. A window looking like this should pop up. Select 'apply to all' and click 'replace'. 7. With the modpack folder still selected again, press 'command' and 'a' at the same time to select all the files, and right click one of the files. Find 'compress X files' (where X is the amount of files), and click it. 8. In the same folder, scroll down to see the only file still selected. It will be called 'Archive.zip'. Place 'Archive.zip' in the 'bin' folder you found at the beginning of this tutorial. 9. The final step. This is very important. Rename the 'Archive.zip' into 'modpack.jar' (without the quotes). The file icon should change. ---------------------------------- That is all you need to do! Now just start up Hexxit, and enjoy! If you have any questions or comments, please post them in the comments. Thank you.