  We give a detailed analysis of pairs of vector and hypermultiplet theories
with N=2 supersymmetry in four spacetime dimensions that are related by the
(classical) mirror map. The symplectic reparametrizations of the special
K\"ahler space associated with the vector multiplets induce corresponding
transformations on the hypermultiplets. We construct the Sp(1)$\times$Sp($n$)
one-forms in terms of which the hypermultiplet couplings are encoded and
exhibit their behaviour under symplectic reparametrizations. Both vector and
hypermultiplet theories allow vectorial central charges in the supersymmetry
algebra associated with integrals over the K\"ahler and hyper-K\"ahler forms,
respectively. We show how these charges and the holomorphic BPS mass are
related by the mirror map.
