This thesis presents the results of a numerical calculation of the light hadron spectrum in the lattice formulation of Quantum Chromodynamics. Results were obtained in both the quenched approximation, where the effects of quark loops in the QCD vacuum were neglected, and in "full" QCD, where two degenerate flavours of dynamical fermions were included in the simulation. All numerical simulations employed the standard Wilson gauge action with an O(a) improved Wilson fermion action. This study confirms that the quenched light hadron mass spectrum agrees with experiment at the 10% level. Finite size effects at one value of the coupling were investigated and an improved scaling behaviour arising from the implementation of the O(a) improvement programme was observed for the quenched simulations. With the aim of observing effects in the spectrum due to the inclusion of fermion loops in the QCD vacuum, simulations in "full" QCD forming a matched ensemble were compared with a quenched simulation at the same lattice spacing. Each simulation in the method ensemble was selected to have approximately the same lattice spacing as defined with respect to a physical observable in order to investigate chiral extrapolations independently from continuum extrapolations. A further simulation with a lighter sea quark mass at a smaller lattice spacing was included in the analysis for comparison. Evidence for small yet significant dynamical effects arising from the comparison with the quenched data were observed in the hyperfine splitting and partially quenched chiral extrapolations. Results obtained from the matched ensemble displayed a reduced residual dependence upon lattice artifacts.