This thesis investigates species diversity and patterns of molecular evolution in the phylum Echinodermata. The first chapter tests and confirms the utility of DNA barcoding for species identification in 131 species of echinoderms. The impact of larval development and dispersal on intraspecific divergence is examined for trans-oceanic and putative cryptic species. The second chapter investigates the association between rates of molecular evolution and developmental mode by employing phylogenetically independent comparisons between species with contrasting modes of larval development (e.g., planktotrophy vs. maternal brood-protection). The results show that species with nonpelagic development have accelerated rates of evolution when compared to those with pelagic development. However, further investigation is required to determine the factors responsible for this trend. These results suggest that reproductive mode is an important factor in the establishment and maintenance of patterns and rates of genetic divergence in echinoderms.