This disclosure provides systems, methods and apparatus for low-profile lighting systems. In one aspect, an LED-based light engine, which may be thinner and/or lighter than conventional light engines, may be retained in both conventionally-dimensioned and low-profile light fixtures. In another aspect, a light engine can include both convective and conductive heat transfer components, the efficacy of which will vary based on the dimensions of a light fixture in which the light engine is installed.