This volume explores geological boundaries in time and space using palynology and micropalaeontology. Boundaries produce distinct signatures in the micropalaeontological record. Diffuse or sharp, gradual or abrupt, boundaries can tell us much about the response of biotic systems to environmental change in both marine and terrestrial realms. Different microfossil groups and geological contexts require their own approaches, definitions and considerations of boundaries. The papers in this compilation capture the current range of thinking on the methodology of boundary identification from biostratigraphical, ecological and palaeoenvironmental perspectives. Contributions span the Cambrian to Miocene and feature many fossil groups (including pollen, dinoflagellates, foraminifera, ostracodes, conodonts, and diatoms). With a strong Canadian and North American focus, the volume also includes contributions from Poland, Egypt, Belgium, Argentina and the United Kingdom.