A linear luminaire having high ingress protection includes a light-generating assembly and a channel. The light-generating assembly is an elongate, self-contained, sealed optical assembly that includes all elements necessary to generate light and to direct, focus, or modify the generated light in a particular way. Typically, the light-generating assembly would include an outer optical element and a light source positioned within a cavity of the body of the light-generating assembly. The outer optical element may be a lens, diffuser, or other such element. The light source may be a strip of LED linear lighting, a string of connected LED modules, or any other suitable device. The light-generating assembly may optionally include a second optical element, such as a lens or diffuser, that is supported within the body. The ends of the body of the light-generating assembly may be sealed by fitted endcaps, by polymeric resin, or by other means.