Christopher Sachrajda has made significant contributions to the development of quantum chromodynamics (QCD) and the theory of the strong interactions. His work on the factorisation of mass singularities led to the perturbative prediction of many physical quantities in strong interaction physics. With others, he pioneered the calculation of higher-order corrections to deep inelastic structure functions, which has led to detailed tests of QCD and the determination of the momentum distribution of quarks and gluons inside the proton. He has played a leading role in the development of the lattice formulation of QCD into a quantitative non-perturbative technique and in the use of this formulation to compute, from first principles, a number of physical quantities, including deep inelastic structure functions, electromagnetic form factors of hadrons and semi-leptonic decays of charmed mesons.