Given the great success of the conservation of orbital symmetry to understand pericyclic reactions, it should come as no surprise that computational chemistry has been widely applied to this area. This chapter discusses a few reactions where either computational chemistry has served to broaden one's insight into pericyclic reactions or where these studies have helped discern the limitations of computational methods. The chapter uses the Diels-Alder reaction and Cope rearrangements to define which computational methods are appropriate for studying pericyclic reactions. Next, it explains the role computational chemistry played in determining the mechanism of the Bergman cyclization and defining the category of bispericyclic and psuedopericyclic reactions. The chapter concludes with a discussion on torquoselectivity, an extension of the orbital symmetry rules developed largely from the results of computational chemistry.