Valence orbitals of the ground electronic state of nitrous oxide (X(1)Sigma (+)) have been studied in configuration space using an ab initio direct multiconfiguration self-consistent field (MCSCF) method and a density functional theory method, which also applied the generalized gradient approximation. The configuration space valence wave functions of the molecule were then transformed to momentum space using the Dirac-Fourier transform. The differential cross sections (i.e., momentum distributions (MDs)) of the valence molecular orbitals (MOs) are calculated in this work using the plane wave impulse approximation. These MDs exhibit excellent qualitative agreement with the available experiments, clearly superior to any previous theoretical calculations. The results from our MCSCF calculations also provide details of the contributions from each of the component atomic orbitals to the valence molecular orbitals. This provides a solid theoretical interpretation for the symmetry and shape (momentum distribution as a function of momentum) of each of the MOs in momentum space. The present work additionally indicates the need for more accurate experimental momentum distributions of N2O, particularly in the low-momentum region. Theoretical improvements, which might reduce the discrepancies between experiment and theory, are also discussed.