Higher Twist Effects in Quantum Chromodynamics.

This dissertation is a study of higher twist effects in QCD in e('+)e('-) annihilation and hadron-hadron scattering. We find in the first case that including mass corrections to O((alpha)(,s)) in the thrust reduces the estimate of non-perturbative effects substantially. In hadron-hadron scattering, we study one loop soft gluon effects and find that factorization of the type suggested by Politzer holds at order m('2)/s but is broken at order m('4)/s('2).