This volume presents a series of case studies, at different levels of inclusivity, of how organisms exhibit functional convergence as a key evolutionary mechanism resulting in responses to similar environmental constraints in mechanically similar ways. The contributors to this volume have selected and documented cases of convergent evolution of form and function that are perceived to be driven by environmental abiotic and/or biotic challenges that fall within their areas of expertise. Collectively these chapters explore this phenomenon across a broad phylogenetic spectrum. The sequence of chapters follows the organizational principle of increasing phylogenetic inclusivity, rather than the clustering of chapters by perceived similarity of the phenotypic features or biomechanical challenges being considered. This is done to maintain focus on the evolutionary phenomenon that is the primary subject matter of the book, thereby providing a basis for discussion among the readership about what is necessary and sufficient to justify the recognition of functional convergence. All chapters stress the need for integrative approaches for the elucidation of both pattern and process as they relate to convergence at various taxonomic levels.