  The structure of a dressed quark is utilized to evaluate the structure
function of proton and pion. It is found that there is a simple relationship
between $F_{2}^{p}$ and $F_{2}^{\pi}$. The ambiguity in the normalization of
$F_{2}^{\pi}$ is discussed. Furthermore, the polarization structure function of
the constituent (dressed) quark is calculated in the leading order. While, it
does produce all the available data on polarized hadronic structure, it
requires a significant contribution to the proton spin from the orbital angular
momentum.
