Echinoderms are a highly diverse phylum of marine invertebrates with a good fossil record that extends back 550 million years. The work presented here is a contribution towards documenting their long history both in terms of phylogenetic branching pattern and evolutionary biology. Taxonomy is the primary means by which evolutionary processes can be studied because it is through taxonomy that species are recognised and their relationships to one another established. Taxonomy at various levels thus forms a major part of the thesis. Species are documented and described both for specific time intervals and within monophyletic groups. Relationships above species level are derived employing cladistic methodology and used to investigate various evolutionary concepts (e.g. the molecular clock; periodicity of extinction). Much of this work deals with the phylogenetic relationships of echinoids at various taxonomic levels, but the relationships of major groups within the phylum are also investigated cladistically. Class relationships have been clarified and revised. By combining data on phylogenetic relationships with those on stratigraphical occurrence, evolutionary trees are constructed which are then used to investigate current ideas on evolutionary processes. Topics investigated include punctuated versus gradualistic evolution, periodicity of extinction, the nature of the Cambrian radiation and the 'Red Queen hypothesis'. Artefact produced by taxonomic convention is recognised as a serious problem in many palaeobiological studies. The evolving relationship between echinoderms and their environment is investigated from a functional morphological point of view. Work of Recent faunas provides the key to understanding morphological variation in the fossil record. Evolutionary changes are documented through time and interpreted in biological terms for specific topics, such as tooth ultrastructure, ambulacral arrangement and trace fossil morphology. The relationship of fossil biotas to tectonic events and their application to palaeogeographical reconstruction is investigated quantitatively, both for echinoids and other groups.