We study the elastic and radiative π<SUP>+</SUP>p scattering within a full dynamical model which incorporates the finite width effects of the Δ<SUP>++</SUP>. The scattering amplitudes are invariant under contact transformations of the spin 3/2 field and gauge-invariance is fulfilled for the radiative case. The pole parameters of the Δ<SUP>++</SUP> obtained from the elastic cross section are m<SUB>Δ</SUB> = (1211.2±0.4) MeV and Γ<SUB>Δ</SUB> = (88.2±0.4) MeV. From a fit to the most sensitive observables in radiative π<SUP>+</SUP>p scattering, we obtain μ<SUB>Δ</SUB> = (6.14±0.51)e/2m<SUB>p</SUB> for the magnetic dipole moment of the Δ<SUP>++</SUP>.Facultad de Ciencias Exactas