  I review, with some pedagogy, two different approaches to the computation of
BPS spectra in N=2 supersymmetric QCD with gauge group SU(2). The first one is
semiclassical and has been widely used in the literature. The second one makes
use of constraints coming from the non perturbative, global structure of the
Coulomb branch of these theories. The second method allows for a description of
discontinuities in the BPS spectra at strong coupling, and should lead to
accurate test of duality conjectures in N=2 theories.
