Silicon Drift Detectors (SDDs) have been selected to equip the two intermediate layers of the Inner Tracking System (ITS), of the ALICE experiment, since they couple a very good multitrack capability with dEldx information and excellent spatial resolution as described in references. In this paper we describe the different components of the SDD system as well as the procedures of the system assembly. (c) 2007 Elsevier B.V. All rights reserved.