AbstractThe paper describes the introduction of the Marshall stability test into commercial use in the U.K. and discusses the practical problems which have arisen. Information is given regarding the influence of aggregate grading and particle shape, and of variation in the percentage and nature of the binder employed. It is shown that particle shape is of greater importance than grading, although the latter can be critical and may have a considerable bearing on the optimum binder content. Lower‐penetration bitumens give generally higher stabilities provided that appropriate changes are made in the compaction temperature. For highways, the use of the Marshall test may give mixtures of relatively low durability. It is suggested that B.S. 594 for hot‐rolled asphalt provides an adequate margin of safety against deformation under most highway conditions without the use of a stability test. It is, nevertheless, suggested that the Marshall test should be further investigated in connexion with road surfacing.