Methods of investigating generalized spatial clustering of disease in human populations have only recently become available. This volume presents the outcome of a unique practical test of these methods, in which authors of several newly developed approaches evaluate their own blind analyses ofover 50 artificial datasets, some random, some generated by clustering processes. Results were then compared with the known spatial structure. An historical view of leukemia clustering is also included. This book will be of particular interest to epidemiologists and public health specialists with responsibliity of analysing childhood leukemia and other rare diseases for which the phenomenon of clustering may offer important clues to aetiology. It will also be useful for statisticians with aninterest in analysis of spatial distributions of rare disease.