Direct-lit backlights and associated methods are disclosed in which an array of elongated light sources is placed in a cavity between a diffuser plate and a back reflector. The back reflector is a specular reflector that can have a divergence half-angle of about 10 degrees or less. The diffuser plate can be of the type that has uniform diffusing properties over its useful area. Appropriate placement of the diffuser plate, light sources, and back reflector can yield a backlight having exceptional thinness, brightness uniformity, and average brightness.