3D printing is offering a totally new construction method, but an in-depth understanding of the consequences of the different production conditions compared to traditional formwork-based casting operations is required. Bulk material properties (intrinsic strength and durability) will follow the same fundamental material laws. However, in printed structures, the role of the interfaces will become increasingly important as they affect the mechanical performance, transport properties and durability behaviour. Additionally, the anisotropic nature of 3D printed structures implies that there are new opportunities to develop new methods of analysis. The aim of this chapter is to focus on the current practices for performance testing and to give an overview of the parameters which affect the hardened properties of a printed cementitious material.