  We discuss non-perturbative QCD corrections to jet distributions in hadron
collisions, focussing on hadronisation and underlying event contributions.
Using soft gluon resummation and Monte-Carlo modelling we show that
hadronisation dominates at small values of the jet radius R, behaving as 1/R,
while underlying event corrections grow with the jet area. This provides a
handle to disentangle them and parametrize them in terms of measurable QCD
parameters, which might enjoy a degree of universality.
