[en] The parallel current in a toroidally-conformed plasma is shown to generally consist of the current in response to the parallel electric field, the Pfirsch-Schluter current which is required by charge neutrality, and the bootstrap current which flows to maintain a balance between the viscous and friction forces along the magnetic field. The steady-state momentum equation is solved to obtain an expression for the parallel current in terms of the electric field and the neoclassical cross-field fluxes of particles and heat in a multiple ion species plasma. It is found that the presence of impurities does not alter the magnitude of the bootstrap current. Thus, the neoclassical beta limit established by the bootstrap current is insensitive to the impurity content of the plasma. The magnitudes of the bootstrap current and conjugate Ware fluxes are investigated in the transition from the long mean-free path to collisional regime