Preface. Conceptual aspects of the quantification of the extent of biological diversity. Biodiversity at the molecular level: the domains, kingdoms and phyla of life. The quantification of plant dioversity through time. Phylogenetic pattern and the quantification of organismal biodiversity. Biodiversity at the molecular genetic level: experiences from disparate macroorganisms. Theoretical and practical aspects of the quantification of biodiversity among microorganisms. Selecting indicator taxa for the quantitative assessment of biodiversity. The quantification of biodiversity: an esoteric quest or a vital component of sustainable development. A comparison of the efficiency of higher taxa and species numbers in the assessment of the biodiversity in the neotropics. Estimating terrestrial biodiversity through extrapolation. Practical approaches to the estimation of the extent of biodiversity in speciose groups. Index.