Structural health monitoring (SHM) using guided waves (GW) is a viable option in composite structures due to their tunable sensitivity to different defects and their ability to interrogate large structural surfaces. This paper presents a 3-D elasticity-based theory for guided wave excitation and propagation in composite materials by finite-dimensional transducers. An overview of the theoretical formulation is presented, and the expressions for the displacements induced by a circular transducer are derived. Experimental attenuation results obtained in a cross-ply and quasi-isotropic composite laminates are used to assess the accuracy of the theoretical solution.