SYNOPSIS. Living corals are routinely collected and shipped to destinations thousands of miles from their point of origin. The fact that corals can survive the rigors of collecting, transport, and acclimation to totally artificial environments was considered impossible not long ago, but hobbyists and some researchers have persevered and have developed aquarium systems and techniques capable of maintaining corals in apparently healthy condition for many years. In particular, new lighting equipment, advances in the control of water chemistry, and new technology for simulating water movement have all contributed to the ability to keep corals alive indefinitely in captivity. Despite the completely artificial conditions of most aquariums, coral extension rates and calcification rates in some aquarium systems are close to those reported for natural reefs, although anomalies have been observed such as decreased skeletal density and unusual changes in colony morphology. Nonetheless, aquariums present real opportunities to culture corals for a variety of bioassay, medicinal, and conservation purposes. As model reef communities (“microcosms”), these systems allow us to test hypotheses concerning the effects of rapidly changing environmental conditions.