[en] A two-component Pauli equation for a composite model of the nucleon is derived using a relativistically covariant quark model. Results are presented as an expansion in the momentum and in derivatives for scalar-isoscalar, vector-isoscalar, vector-isovector and electromagnetic external potentials. The Dirac equation fails beginning with the magnetic moment and spin-orbit terms; the failure is modest for isoscalar potentials, but is large for the isovector case. For the vector fields we find anomalous ''magnetic moments'', which are simply related to the corresponding electromagnetic κ. Preliminary results involving the fields quadratically are also presented. 13 refs