The answer is YES but you have to go through some tuning steps. I did the following test on an iMac running macOS Sierra 10.12 (16A323) that never ran IDL before (=fresh install). 1- Install Quartz 2.7.9 https://www.xquartz.org/ (XQuartz-2.7.9.dmg). Make sure your security settings allow the install of this package. SUCCESS 2- Download Install_IDL85ENVI53SP1.pkg and install it (As for Quartz, make sure your security settings allow the install of this package). Follow the instructions. Uncheck ENVI if you don’t use it. SUCESS 3- In the launchpad, a new group of software appears ‘exelis’. Run the LicenseWizard : FAILED. An xQuartz xterm opens on the following prompt (user@computer:~$) but nothing else happens. 4- Run idlde.darwin.x86_64 (from the Launchpad group ‘exelis’): a pop-up window appears asking you to use the old Java SE 6 engine (same issues were reported with older OS X (macOS) versions). Click the ‘More info’, you’ll be redirected to https://support.apple.com/kb/DL1572 in order to download Java 2015-001 from apple (javaforosx.dmg) 5- Close all Apps using Java. 6- Install Java using the downloaded javaforosx.dmg file. 7- Run idlde.darwin.x86_64 (from the Launchpad group ‘exelis’): SUCCESS but IDL is still asking you for the license as the LicenseWizard failed to launch. Fortunately, the pop-up window asks you for a license file (license.dat or license.lic in one of some specific paths) : note them. 8- Manually place your personal license.dat file in the license path (/Applications/exelis/license/ in my case). Note, that you may have to use an admin account to be able to place the license file there. 9- Run idlde.darwin.x86_64 (from the Launchpad group ‘exelis’): SUCCESS! Summary: 1. Install the latest xQuartz version. 2. Install Java for 2015-001 (Java 6SE) 3. Install IDL 8.5.1 4. LicenseWizard doesn’t run on macOS Sierra -> place the license.dat file manually in the license path. 5. Run IDL The question now is: will it crash or bug someday? Time will tell. Optional: I also renamed ‘idlde.darwin.x86_64' to a sexier ‘idl’ in the Applications folder (a symbolic link will also do the job). PS to the webadmin: My original thread (Your post IDL on macOS Sierra posted on 9/22/2016 7:02:35 AM in forum IDL has been approved) is unreachable, so I created a new one.