  In this thesis a general relativistic framework for the calculation of the
electroweak structure of mesons of arbitrary constituent-quark masses is
presented. The physical processes in which the structure is measured, i.e.
electron-meson scattering and semileptonic weak decays, are treated in a
Poincar\'e invariant way by making use of the point-form of relativistic
quantum mechanics. The electromagnetic and weak meson currents are extracted
from the 1-photon or 1-W-exchange amplitudes that result from a
Bakamjian-Thomas type mass operator for the respective systems. The covariant
decomposition of these currents provides the electromagnetic and weak
(transition) form factors. The formalism is first applied to the study of
heavy-light systems. Problems with cluster separability, which are inherent in
the Bakamjian-Thomas construction, are discussed and it is shown how to keep
them under control. It is proved that the heavy-quark limit of the electroweak
form factors leads to one universal function, the Isgur-Wise function,
confirming that the requirements of heavy-quark symmetry are satisfied. These
results are discussed and compared with analogous calculations in the front
form of dynamics. The formalism is further applied to the study of bound states
whose binding is caused by dynamical particle exchange. The problem of how to
take into account retardation effects in the particle-exchange potential is
formulated and it is shown how they affect the binding energy and wave-function
solution for a dynamical model of the deuteron. At the end of this work an
example where the Clebsch-Gordan coefficients of the Poincar\'e group are
applied is presented. The angular momentum decomposition of chiral multiplets
is given in the instant and in the front forms.
