This Brief Communication presents an alternative approach for determining the Landau constants associated with the implementation of weakly nonlinear theories. Results from this approach are shown to be in agreement with the usual solvability condition for the case of exact resonance. Away from resonance, the results are in agreement with a direct solution of the nonhomogeneous system. This approach also provides accurate results for the case of near resonance, in contrast to the approach currently in widespread use. Following this alternative approach, the Landau constants can be calculated accurately in a straightforward manner without requiring the solvability condition in some arbitrary neighborhood of resonance.