Low symmetry materials such as hexagonal metals and alloys, deform by twinning as well as by slip, with twinning making a substantial contribution to deformation, hardening and texture evolution. In this work, we present an experimental and theoretical study of hexagonal Zr, Be and Mg aggregates with an initial texture, deforming in compression. The evolution of texture and twinned volume fraction were measured using neutron diffraction. Complementarily, a polycrystal plasticity code was used to interpret texture and hardening evolution in terms of interaction between slip and twin modes. This study correlates twinning, texture, anisotropy and hardening. It represents a systematic approach for understanding the plastic response of hexagonal materials and for developing a microstructure-based constitutive description.