  Expressions for the nucleon wave functions in the covariant spectator theory
(CST) are derived. The nucleon is described as a system with a off-mass-shell
constituent quark, free to interact with an external probe, and two spectator
constituent quarks on their mass shell. Integrating over the internal momentum
of the on-mass-shell quark pair allows us to derive an effective nucleon wave
function that can be written only in terms of the quark and diquark
(quark-pair) variables. The derived nucleon wave function includes
contributions from S, P and D-waves.
