Numerical calculations of particle motion through a model magnetotail neutral sheet are carried out. The component of the magnetic field normal to the neutral sheet is assumed constant, and the component parallel to the sheet is assumed to vary as the hyperbolic tangent. A constant electric field perpendicular to the plane of the magnetic field is assumed. It is shown that one encounter of plasma with the neutral sheet is sufficient to convert plasma with lobe, or mantle, characteristics into a plasma with properties typical of the plasma sheet. For a range of parameters a neutral sheet encounter produces a monoenergetic distribution sharply peaked at a particular pitch angle. Neutral sheet encounters increase the pitch angle to the extent that plasma particles would be expected to mirror at large distances from the earth. The lack of particles in the distant magnetosphere that have mirrored is used to suggest that streaming plasma sheet particles may constitute an energy source for the aurora.