This chapter considers the assessment and role of aggregates for use in Asphalts for highway construction. Any Asphalt, whether Hot Rolled Asphalt, Bitumen Macadam, Porous Asphalt, Stone Mastic Asphalt or Surface Dressing is nothing more than a specified blend of aggregate and bitumen. When mixed and laid properly, a durable and long lasting structure should result. However, what properties must the aggregate have to ensure that this occurs? This chapter considers the basic test methods available to the Engineer which enable him to make a choice. It also considers the factors that influence these procedures.