Aggregation-induced emission (AIE) stands for an intriguing phenomenon in which a series of non-emissive molecules in solutions are induced to emit strongly in the aggregate or solid state. The concept of AIE was first coined by author Ben Zhong Tang in 2001, when he and his co-workers serendipitously discovered that 1-methyl-1,2,3,4,5-pentaphenylsilole was almost non-emissive in ethanol solution but became extremely bright in water-ethanol mixtures. Over the past 15 years, AIE has grown into a research field with high visibility and broad impact across both science and technology. Aggregation-Induced Emission: Materials and Applications summarizes the recent advances in AIE research, ranging from fundamentals, such as design, synthesis, and optical properties of AIE-active molecules, to mechanism studies supported by modeling and experimental investigations, and further to promising applications in the fields of energy, environment, and biology. Because of the large amount of excellent research, the contents have to be divided into two volumes, with Volume 1 focusing on materials and Volume 2 placing greater emphasis on applications. The topics covered in Volume 1 include: New mechanisms and theoretical understanding of AIE phenomena; Vibration-induced emission; The art of restriction of molecular rotation; Domino synthesis of AIE molecules; Small molecule AIE systems; and Mechanochromic AIE materials.