An edge lit luminaire includes a light source. A housing has an interior cavity for receiving the light source. The housing includes a heat sink for directing heat away from the light source. At least one optional end cap is secured to an end of the housing that covers the cavity. A lightguide is secured inside the housing and has an edge located in proximity to the light source. At least one of a reflector and a lens (e.g., lens optic) directs light from the light source to the edge of the lightguide. The lightguide includes a light extraction surface enabling light to be transmitted from the lightguide. The housing can also feature a channel and slot for mounting the luminaire to a support surface. The lens optic can be designed to have specific dimensions that facilitate efficient design and operation of the luminaire.