Species identification is one of the most important uses of DNA barcoding, allowing researchers to be able to quickly identify a species without the often expensive and time-consuming process of consulting a specialist. Some animal groups are very difficult to identify and are currently lacking DNA barcodes for simple species identification. One of these groups are marine free-living polyclad flatworms. This group is found worldwide with over 1000 species classified into 27 families and almost none of these have DNA barcodes available. However, commonly employed primers to amplify mitochondrial COI for diverse animals unfortunately do not work for polyclads. Thus, we designed polyclad-specific primers and have successfully tested them with California polyclad species, well representing taxonomic diversity within the group. The resulting COI sequences will be made available internationally and will become one of the results of our study. Here, we are reporting the first-ever regional DNA barcode study of polyclads, and have supported it with the morphological identification of vouchered specimens, generously contributed by worm experts. We are also involved in testing non-lethal means to extract genomic DNA from polyclad mucus, which will enable researchers to positively identify living specimens for a variety of biological studies. Because polyclads have tremendous reproductive diversity, DNA barcoding could also be used to relate diverse plankton-collected polyclad larvae to the adults living on nearby shores, providing yet another means of identification.