Mg is a lightweigh t structural material with a good specific strength. Unfortunately, it lacks sufficient room temperature formability and therefore a wider commercial use of Mg is hindered. The preferred basal slip and strong basal-type texture were found to be the main reasons for the poor room temperature formability. Alloys containing low amounts of Al and Ca showed a highly increased room temperature ductility. Here, TEM measurements and ab initio calculations showed an increased activity of < c+a > dislocation slip. The effects of the alloying elements are yet not fully understood. Further research has been performed to investigate how the changes in chemistry affect the structure of defects such as boundaries and dislocations.