The determination of how much generating capacity is required in an electric power system is a basic element in power system planning. A second and equally important aspect of the planning process is the development of a suitable transmission system to move the generated energy to the major load points. Adequacy evaluation of composite generation and transmission systems is a complex task that includes detailed modeling of the generation and transmission facilities. The emergence of wind generation as an important electrical energy source creates some challenging complications in evaluating the adequacy of composite systems, as wind power behaves quite differently than conventional electric power generating facilities. This chapter discusses the general area of composite system adequacy evaluation and some of the various techniques that can be utilized to incorporate wind power in a system assessment. Wind power modeling in both generation and composite system adequacy evaluation is discussed and illustrated by application to two well-known reliability test systems. The studies presented utilize sequential and non-sequential Monte Carlo simulation and illustrate the addition of independent and correlated wind generation to the two test systems.