In a previous paper [F.A. Haas and J.A. Wesson, Phys. Fluids 9, 2472 (1966)] the hydromagnetic stability of a β = 1 theta‐pinch with a sharp boundary was considered. This work is here extended to a study of β < 1. Stability criteria are obtained and in particular it is shown that the m = 1 mode is stable if (1 ‐ β) < (R/Rw)2 everywhere along the pinch, where R and Rw are the radii of the plasma and conducting wall, respectively. The case of a distributed radial pressure gradient is also considered.