Equipment for continuous equal channel angular processing (CECAP) of sheet, developed at Monash University, was used to investigate the large-scale mechanical properties of several work hardenable Al-Mg alloys (AA5xxx series) processed by CECAP. The major purpose of this work was to seek parameters for prediction of processability, as predictors of surface quality, formability and limits of deformation and as a preliminary for on-line control of the process. The emphasis of the work was on formability and surface quality rather than on strength properties. It does not attempt to represent processing under optimum conditions. A general correlation of mechanical properties with the work hardening exponent and with a measure of strain-rate sensitivity confirms the significance of these parameters. However, the limited value of macroscopic mechanical parameters determined in prior tensile tests for predicting processability of sheet by CECAP was attributed to strong dependence on the evolving microstructure. As might be expected, a stronger correlation with the properties of sheet tested following processing was found. A modest increase in the strength of the lower Mg alloys AA5005 and AA5052 was generally lost or greatly reduced due to recovery at ambient temperature. The effect of CECAP on the strength of the higher Mg AA5086 apparently depended greatly on the initial condition of the alloy. A 30% increase in the coefficient of normal plastic anisotropy of AA5086 sheet annealed after two CECAP passes pointed to an increase in biaxial formability, but was not realised in sheet subjected to a greater number of passes.