  Long term sustainability of the high energy physics (HEP) research software
ecosystem is essential for the field. With upgrades and new facilities coming
online throughout the 2020s this will only become increasingly relevant
throughout this decade. Meeting this sustainability challenge requires a
workforce with a combination of HEP domain knowledge and advanced software
skills. The required software skills fall into three broad groups. The first is
fundamental and generic software engineering (e.g. Unix, version control,C++,
continuous integration). The second is knowledge of domain specific HEP
packages and practices (e.g., the ROOT data format and analysis framework). The
third is more advanced knowledge involving more specialized techniques. These
include parallel programming, machine learning and data science tools, and
techniques to preserve software projects at all scales. This paper dis-cusses
the collective software training program in HEP and its activities led by the
HEP Software Foundation (HSF) and the Institute for Research and Innovation in
Software in HEP (IRIS-HEP). The program equips participants with an array of
software skills that serve as ingredients from which solutions to the computing
challenges of HEP can be formed. Beyond serving the community by ensuring that
members are able to pursue research goals, this program serves individuals by
providing intellectual capital and transferable skills that are becoming
increasingly important to careers in the realm of software and computing,
whether inside or outside HEP
