  Eta meson production in both proton-proton and proton-neutron collisions is
investigated within a relativistic meson exchange model of hadronic
interactions. It is found that the available cross section data can be
described equally well by either the vector or pseudoscalar meson exchange
mechanism for exciting the S_{11}(1535) resonance. It is shown that the
analyzing power data can potentially be very useful in distinguishing these two
scenarios for the excitaion of the S_{11}(1535) resonance.
