In conclusion, we report on a novel three-state aza-diarylethene photoswitch 1 that allows advanced control over three states and enables highly versatile applications. Reversible and quantitative photoswitching under forming and breaking a C=N double bond is achieved when alternating between the isomers open 1 and closed Z-1. Further, selective and also quantitative enrichment of a third isomer, closed E-1, in a third photostep is possible. This isomer emerges through a consecutive double bond isomerization of closed Z-1 upon irradiation at a different wavelength. The wavelength-depend advanced control over enrichment of either closed Z-1 or closed E-1 allows to alter the system from a thermally highly labile to an extremely stable one.