Luminescent molecules with high efficiency in aggregate state are promising candidate materials for the development of organic light-emitting diodes, fluorescent sensors, solid-state lasers, and so on. The discovery of aggregation-induced emission (AIE), whereby the aggregation of luminogens plays a positive role, enhancing the light-emission efficiency, has attracted much interest as it offers a new platform for the exploration of practically useful luminescent materials. This Faraday Discussion brings together researchers in the field to discuss the progress made so far, current challenges and potential breakthroughs that may be accomplished in the near future. It focuses on the issues associated with the development of new fluorescent and phosphorescent AIEgens, particularly the advanced functional AIEgens with stimuli-responses, and the exploration of high-tech applications of the AIEgens, especially in the area of biomedical research.