Monopole--Instantons in M2-brane Theories

We study monopole-instantons in M2-brane theories, focussing on the ABJM class of Chern-Simons gauge theories coupled to matter. We calculate calculate explicitly the 8-fermion term in the effective action induced by these monopole-instantons, and discuss their role in resolving a classical singularity in the moduli space. The results are compared with monopole-instantons in N=8 3d SYM and D-brane theories, as well the dual supergravity description as a membrane scattering process.