The behavior of charged particles in an ultralow frequency magnetospheric pulsation with standing wave structure along the magnetic field is interpreted by using a graphical approach. Attention is directed principally to the way in which particles are accelerated as they bounce and drift through a wave with which they are in resonance, but nonresonant particles are also discussed. Under appropriate conditions, passage through the wave leads to modulation of particle energy. Applications emphasize the necessity of considering the large-scale structure of a wave in interpreting the particle behavior seen at a particular point in space.