Great attention has been recently paid to the investigation of plastic deformation in NiTi. Experimental investigations of the mechanical response of NiTi polycrystalline samples within a broad stress-strain-temperature state space have revealed a complex response involving martensitic transformation, reorientation, and plastic deformation processes. The interactions between them result in complex coupled phenomena, such as transformation-induced plasticity, martensite stabilization through plastic deformation, and micro-strain heterogeneity induced by plasticity. Plastic deformation in NiTi not only generates irrecoverable strain at the macroscale, but it also induces substantial strain heterogeneity in the microstructure. This heterogeneity significantly affects the functional properties and may open up new technology pathways for designing sophisticated products. Tailored constitutive models that can reproduce the response in complex loading scenarios can be extremely beneficial.