David Edwards has conducted important and wide-ranging studies of quantum fluids and solids, enhanced by the elegant application of thermodynamics. After early work at Oxford on heat conduction in superfluid helium-4, his work has been mainly with the school founded by John Daunt that he built up at Ohio State University. He made the first observations of the melting curve of helium-3–helium-4 mixtures, and of the finite solubility of helium-3 in liquid helium-4 at T > 0, followed by a definitive study of the thermodynamic and transport properties of dilute helium-3–helium-4 solutions. He pioneered the study of the liquid helium-4 surface, particularly the effect of small amounts of helium-3, and has also done innovative work on the liquid–solid interface and the roughening transition. Recent work at millikelvin temperatures has led to the observation of collisionless spin waves in normal and superfluid helium-3.