Illumination assemblies, components, and related methods are described. An illumination assembly can include at least one solid state light-emitting device, an emission surface through which light is emitted, and a wavelength converting material that wavelength converts at least some light emitted by the solid state light-emitting device. The wavelength converting material can have a first density per unit area of the emission surface at a first location and a second density per unit area of the emission surface at a second location, wherein the second density is substantially different from the first density, and wherein the density per unit area is defined with a 1×1 cm2 averaging area. Another illumination assembly can include a light guide configured to receive light emitted by a solid state light-emitting device. The light guide can have a length along which received light propagates and an emission surface substantially parallel to the length of the light guide and through which light is emitted. A wavelength converting material can have a density per unit area of the emission surface that substantially increases along the length of the light guide.