This paper presents a novel analysis of the classical electromagnetic scattering from a conducting circular disk. A hybrid method which combines the vector wave eigenfunction expansion technique, the least squares method, the mode-matching method, and the dyadic Green's function is applied to derive the unknown scattering coefficients of the expanded eigenfunctions of scattered fields. Orthogonality of the vector wave functions is also utilized to simplify the problem. The edge effects of the thin conducting circular disk are considered in the formulation of the scattering coefficients. Although coupled to teach other, the scattering coefficients are obtained in a closed form and expressed in terms of compact matrices using the least-squares algorithm. Numerical computation of the radar cross sections (RCS's) of the perfectly conducting disk is carried out. Experimental data and theoretical results published elsewhere are also used to confirm the applicability of the hybrid method developed in this paper.