[en] Parton distribution functions for protons are devised in which a light gluino is included along with standard model quark, antiquark, and gluon constituents. A global analysis of a large set of hadronic scattering data provides empirical constraints on the allowed range of the gluino mass m_g tilde as a function of the value of the strong coupling strength α_s(M_Z). We find that m_g tilde > 12 GeV for the standard model world-average value α_s(M_Z)=0.118. Gluino masses as small as 10 GeV are admissible provided that α_s(M_Z) ≥ 0.12, about one standard deviation above the world-average value. Current hadron scattering data are insensitive to the presence of gluinos heavier than ∼100 - 150 GeV. (author)