A TORQUE WRENCH FOR DNA, an experimental tool for twisting the double-helix molecule at one of its ends, can yield once-elusive information on its mechanical properties. DNA is much more than a database of genetic information; it is a versatile machine that can duplicate itself, build and repair cells, and regulate cell functions. By attaching one end of a DNA molecule to a surface and affixing a tiny magnetic bead to the free end, experimentalists in France devised a clever way to twist a single molecule and stretch it with external magnets (T.R. Strick et al, Science, 29 March 1996). But with heat constantly jiggling the molecule and introducing complicated motions, physicists once feared these experiments would not provide useful data. Now, two theory groups have independently filtered out the contributions of this random motion. Considering a DNA molecule going from an unstretched state to a stretched state, they factor in the possible combinations of random twists and bends that the DNA molecule can exhibit in going towards its final outstretched state. With this theoretical contribution, the experiments can now provide a new determination of an elusive mechanical parameter of DNA, its twisting stiffness (C. Bouchiat and M. Mezard, Physical Review Letters, 16 February 1998; J.D. Moroz and P. Nelson, Macromolecules, September 1998, see Lay Language Paper by Moroz and Nelson.)