  Experimental data of the pion charge form factor are well represented by
Poincar\'e invariant constituent-quark phenomenology depending on two
parameters, a confinement scale and an effective constituent--quark mass. Pion
states are represented by eigenfunctions of mass and spin operators and of the
light-front momenta. An effective current density is generated by the dynamics
from a null-plane impulse current density. A simple shape of the wave function
depending only on the confinement scale is sufficient.
