The newly constructed Regent Street water tower in Fredericton, N.B., Canada, totally collapsed December 19, 1990, during the normal procedure of initial filling. Many samples of materials were taken from the wreckage for testing. All available design documentation and the construction process were thoroughly reviewed in an effort to determine the cause of the catastrophic collapse. In particular, the design of the steel water-storage cell was conducted retroactively for six sets of practical design specifications in use in North America and Europe. Additionally, extensive computerized numerical modeling was employed to study the complex stresses and buckling characteristics of the storage cell. A thorough investigation revealed that the collapse of the Regent Street water tower occurred primarily as the result of a deficient thickness of the lower conical portion of the storage cell. Other factors that may have contributed to the final collapse are discussed, but the extent of their contribution is a complex and largely unquantifiable question. Includes 20 references, tables, figures.