Abstract: A wind turbine bearing system for a rotating main shaft of a wind turbine includes a double-row tapered roller bearing assembly (64) having a one-piece inner race element. The inner race element defines first and second inner raceways. The roller bearing assembly further includes first and second sets of tapered rollers seated within the corresponding first and second inner raceways. The bearing assembly also includes a two-piece outer race element, each piece of the two-piece outer race element defining a respective outer raceway. Each piece of the two-piece outer race element has a cylindrical outer diameter defining an outer contact surface. The system further includes a pillow block housing assembly that defines a cylindrical inner diameter (46) substantially matched to the outer contact surfaces (144,148) of the pieces of the two-piece outer race element to define an interface between the pillow block housing assembly and the bearing assembly.