This session is intended as a discussion forum to review and improve our current understanding of particle acceleration mechanisms in space plasmas, from both experimental and theoretical point of view. In particular, this session will contribute to highlight the current and future synergies between in situ and remote observations, simulations, and theories. Synergism is crucial to establish how fundamental acceleration mechanisms operate in different space plasma environments (e.g. solar corona/wind, planetary magnetospheres, astrophysical objects). Such collaborative approach is strongly motivated by major observational advances obtained with heliophysics spacecraft (Cluster, Themis, MMS, RBSP, Rhessi, Stereo, Hinode, SDO, etc), by upcoming missions such as Solar Orbiter and Solar Probe Plus and by missions under study, such as the THOR mission that has particle energization in turbulent plasmas as major science objective. We solicit contributions on the topic of particle acceleration mechanisms such as those operating in magnetic reconnection regions during solar flares and planetary substorms, in turbulent regions such as the pristine solar wind and planetary magnetosheaths, at interplanetary and planetary foreshocks and shocks, and in radiation belts and auroral regions.