Results from a series of hydrostatic compression, conventional triaxial compression and triaxial compression tests conducted on compacted specimens of unsaturated clayey sand under constant-suction states are presented. The experiments were accomplished in a recently developed true triaxial (cubical) apparatus that is suitable to test cubical, 3-in (7.5-cm) per side specimens of unsaturated soil under controlled-suction states and for a wide range of stress paths that are not achievable in a cylindrical apparatus. Test results are presented in terms of specific volume versus net mean stress response, as well as deviatoric stress versus principal strain response. Matric suction is shown to exert a considerable influence on volume change response and peak shear strength of compacted clayey sand. The new cell is a refined version of a stress-controlled system previously reported by Hoyos et al. (2005, 2008). Target matric suction levels in the specimens are induced and kept constant during testing using the axis-translation technique.