The new generation of Apple Mac comes with the new Apple Silicon (M1) chip which has an Arm architecture (as opposed to the older generation that had i386 Intel processor). This brings all manner of troubles and requirements for the development of codes. Here I detail how to install Underworld on Mac OSX Big Sur 11.5.2 (Apple Silicon) using Python 3.9 Important Note: The following guide uses the CMake branch of Underworld.