In this chapter, we introduce the so-called Classical Laminated Plate Theory (CLPT), which represents a very basic theoretical framework and tool for the mechanical analysis of composite laminates. After presenting the basic assumptions of this laminate theory and clarifying the kinematics and the stress state, we derive the constitutive law of a laminate within the framework of CLPT and familiarise ourselves with the so-called coupling effects that are typical for laminates. This is followed by a discussion of the constitutive law for selected classes of laminates, and the effective properties of laminates are also dealt with. The chapter ends with a presentation of the strain energy of a laminate and the treatment of unsymmetric laminates.