Dear Allin, I think Gretl is ignoring the path to Python executable in OS X (El Capitan). I trying to use a different version of Python (2.7.11) and Gretl is running the old one (2.7.10) that is supplied by Apple. I tried three different paths (under GUI "Tools -> Preferences General -> Programs"): (1) "/Applications/Python 2.7/IDLE.app/Contents/MacOS/Python" (2) "/Library/Frameworks/Python.framework/Versions/2.7/bin/python" (3) "" (empty!) And executed the following commands: <python> import sys print (sys.version) </python> Best, Henrique Andrade