Progress in the study of structure functions in deep inelastic scattering is reviewed. A brief introduction to the formalism and the status of global analyses of parton distributions and their uncertainties is given. The review focuses on recent developments in the following areas: HERA results onF2,FLand charm; the resolution of the CCFR-NMC discrepancy; Tevatron jet cross-sections at different energies; and HERA high-Q2cross-sections and the measurement ofxF3.©2000 American Institute of Physics.