Typical luminophores usually suffer from weakening or quenching of light emission caused by aggregation. This notorious photophysical effect is practically harmful, as luminophores are commonly used for real-world applications in solid state or aqueous media, where they tend to form aggregates. We have discovered a diametrically opposite phenomenon that luminophores are non-emissive when molecularly dissolved and induced to luminesce by aggregate formation. We termed this unusual process as aggregation-induced emission (AIE). A wide variety of AIE luminogens have been developed, which not only possess the conjugated structures, such as tetraphenylethylene and multi-phenyl silole, but also have the non-conjugated polyester and polyamide systems, which have broad emission range covering visible and near-IR region and high luminescence quantum yields. We have demonstrated the great utility of the AIE materials and explored their high-tech applications in such areas as optoelectronic devices, chemo/biosensing and biological imaging.