Unquenching the Quark Model

The formalism for a new generation of unquenched quark models for baryons in which the effects of quark-antiquark pairs are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechanism, is presented. As an application the quark-antiquark contribution to the spin of the proton and the Sigma(+) is discussed. Finally the strangeness radius of the Sigma(+) in the closure limit is calculated.