Pictorial energy (U) landscape for a finite-size set of soft spheres for which thermal fluctuations can be neglected. |r〉 denotes the degree of freedom of particle positions, and ΔL the deformation of the shape of the simulation box. Dagois-Bohy et al. show that jammed states identified by compression-only (CO) methods minimize the energy with respect to the particles’ positions only and may be unstable to shear. Shear-stabilized packings (SS) minimize the energy with respect to both particle positions and the box shape and are thus properly jammed. Goodrich et al. analyze how the properties of shear- and compression-stable states scale with size, finding the evidence that jamming can be described as a true phase transition.