The effect of microstructural features of A356 alloys on plastic deformation behavior was studied in the present study. To authors' knowledge, the microstructural effect on mechanical properties of A356 alloy has not been well understood even though this alloy system is one of the most widely used alloys for the industrial purpose. Specially, quantitative relationship between properties like ductility and fracture toughness with microstructural features is lacking. In the present study, four different processing methods were used to investigate how the size and distribution of primary alpha and eutectic phases influence the plastic deformation characteristics. The prcessing routes for A356 control arm include low pressure casting, squeeze casting, rheo-casting and cast-forging processes. Special focus was given to understand which microstructural features do the beneficial or detrimental effect and how they work.