Dear All, Following the excellent guide that Hiroyuki & Bruce gave for running larch on Demeter on Windows (Ifeffit Digest, Vol 174, Issue 8). The following steps worked for me to run larch/Demeter on MacOS (Sierra 10.12.6). 1) Install Demeter using the advice from: https://bruceravel.github.io/demeter/documents/SinglePage/macinstallation.ht... 2) Installed Anaconda and larch using the following guide: http://cars.uchicago.edu/xraylarch/installation/index.html (Python & larch from source is fine: but then use Hiroyuki’s step 3&4 advice [attached below]) 3) In a new terminal window check larch by: larch --version You should see "larch command-line version 0.2". 4) Running larch and Demeter, run in a new terminal window: larch --port=4966 –rc 5) Open Demeter.pm in a text editor (which for me was buried in: /opt/local/lib/perl5/site_perl/5.24/darwin-thread-multi-2level/Demeter.pm) and change line 44 to: $ENV{DEMETER_BACKEND} ||= 'larch'; 6) This has changed both Athena and Artemis to using larch – haven’t fully tested yet, but looks good. Best Wishes, Luke (from Hhiroyuki, installing python and larch from source files:) 3. Install unofficial Numpy and Scipy, Python libraries 3-1. Download numpy‑1.13.1+mkl‑cp36‑cp36m‑win_amd64.whl and scipy‑0.19.1‑cp36‑cp36m‑win_amd64.whl via http://www.lfd.uci.edu/~gohlke/pythonlibs/ 3-2. pip install numpy-1.13.1+mkl-cp36-cp36m-win_amd64.whl 3-3. pip install scipy‑0.19.1‑cp36‑cp36m‑win_amd64.whl 4. Install Larch and its dependencies 4-1. Start a command prompt 4-2. git clone https://github.com/xraypy/xraylarch.git 4-3. cd xraylarch 4-4. pip install lmfit 4-5. pip install h5py 4-6. pip install pillow 4-7. pip install requests 4-8. pip install sqlalchemy 4-9. pip install matplotlib 4-10. pip install pypiwin32 4-11. pip install wxpython 4-12. pip install wxmplot 4-13. pip install wxutils 4-14. python setup.py install 4-15. larch --version 4-16. You will see "larch command-line version 0.2". Note: I installed Larch dependencies except for pyFAI, CifFile, fabio, tomopy, scikit-image.