A lecture given by David Dye, at the Adventures in the Physical Metallurgy of Steels (APMS) conference held in Cambridge University. Twinning induced plasticity steels as armour. Twinning Induced PLasticity steels have recently been popular topics of research owing to their potential for high energy adsorbtion during deformation. This is a consequence of both their propensity to twin due a an optimised stacking fault energy and also the thinness of the twins, which results in continuous work hardening and hence the avoidance of necking until very high strains are reached. However, not all of this deformation is useable in many applications; for example the hull intrusion in an armoured vehicle may not be manageable beyond a certain point. Therefore there is a desire for TWIP steels with higher initial yield strengths. Here we describe a two options to add strengthening mechanisms to austenitic TWIP steels to provide this strength without damaging the underlying twinning mechanism, and progress we have been making in implementing these in an industrially exploitable steel.