  Nucleon and pion electromagnetic form factors are evaluated in the spacelike
region within a light-front constituent quark model, where eigenfunctions of a
mass operator, reproducing a large set of hadron energy levels, are adopted and
quark form factors are considered in the one-body current. The hadron form
factors are sharply affected by the high momentum tail generated in the wave
function by the one-gluon-exchange interaction. Useful information on the
electromagnetic structure of light constituent quarks can be obtained from the
comparison with nucleon and pion experimental data.
