A light-guide light (1) suitable for use in illuminated displays and signs comprises a housing (3) defining an optical cavity having first and second generally parallel major faces (5, 6), and a light source (11) positioned to direct light into the optical cavity from one side. The first major face (5) comprises a material (for example, a prismatic film) having coefficients of reflection and transmission that vary with the angle at which light is incident on the material. The second major face (6) comprises a narrow-scattering reflective material having a reflectance of at least 85%, for example a highly-efficient reflective material provided with a suitable textured pattern.