  The kaon electromagnetic (e.m.) form factor is reviewed considering a
light-front constituent quark model. In this approach, it is discussed the
relevance of the quark-antiquark pair terms for the full covariance of the e.m.
current. It is also verified, by considering a QCD dynamical model, that a good
agreement with experimental data can be obtained for the kaon weak decay
constant once a probability of about 80% of the valence component is taken into
account.
