According to the "orthodox" model for single electron tunneling, sudden changes in current-voltage characteristics of nanoparticle (NP)-tunnel junction (TJ) systems ["Coulomb blockade" (CB) and "Coulomb staircase" (CS) phenomena] arise fundamentally due to charge quantization. We have embedded NPs (similar to2.5 nm in diameter) in the TJ of a hybrid scanning tunneling-atomic force microscope and have simultaneously measured current and forces generated in the system. We discuss an application to micromechanical switching actuated by single electrons. We also show that CB and CS phenomena are in fact associated with steplike changes in force, directly confirming the discrete charge nature of the phenomena. (C) 2003 American Institute of Physics.