Computational Particle Mechanics (CPM) is a quarterly journal dedicated to publishing original research articles on systematic modeling and simulation involving particles and particle methods. The aim of the journal is to enhance communication among applied science researchers who utilize 'particles' in their studies in one form or another. Specifically, particle-based materials and numerical methods have found extensive applications in natural sciences, applied sciences, and engineering, including biology. For researchers in the 21st century, the term 'particle methods/mechanics' encompasses several different concepts, including: (A) particles as physical units in granular media, granular flows, plasmas, and clusters; (B) particles representing continuous material phases at mesoscopic, micrometer, and nanometer scales; and (C) particles as continuous and discontinuous discrete units in numerical methods such as Discrete Element Method (DEM), Particle Finite Element Method (PFEM), Molecular Dynamics (MD), and Smoothed Particle Hydrodynamics (SPH), among others.