The realization that many essential functions of living cells are performed by nanoscale motors consisting of protein complexes has given rise to an intense effort to understand their mechanisms. Considerable progress has been made in the past two years by a combination of biophysical techniques and theoretical analysis. Single-molecule studies have played a spectacular role for a variety of motors including kinesin, myosin, and polymerases. The understanding of F(1)-ATPase, the smallest biomolecular rotary motor, has made particular progress by the interplay of experimental and theoretical studies; the latter have provided information not available from experiment.