At the 2002 SICB meeting in Anaheim, we brought together some of the leaders in terrestrial and marine phylogeography for a day-long symposium. This symposium combined presentations from ten scientists whose question-driven research focuses on testing hypotheses about patterns and processes in biogeography in both vertebrate and invertebrate animals and including marine, terrestrial, and freshwater systems. The papers gathered here cover the breadth of the presentations. By explicitly seeking to combine marine and terrestrial workers into a single symposium we hoped that the different patterns and processes that predominate in major biomes and the different assumptions made by the workers in those areas would be highlighted.