This SRC is focused on the dynamic nature of mobile DNAs in mammalian genomes and their phenotypic impacts. Topics will encompass mechanistic and evolutionary aspects of diverse types of retrotransposons, including LINE-1 and endogenous retroviruses, as well as DNA transposons and related human genes. Attendees will also explore interactions between these sequences and the epigenome and endogenous machinery of DNA repair and rearrangement. These elements comprise are a major portion of our DNA, and are significant contributors to genomic diversity in the form of structural variation. While the germ line is a well-known site of activity of mobile genetic elements, there is increasing evidence for expression and mobility in somatic cells and in human diseases, particularly cancers. This makes it an exciting time for the field. Moreover, new insights are being gained into roles of mobile elements in shaping gene regulatory networks in normal cells. Finally, harnessing mobile genetics elements as tools for forward genetic screens or gene delivery has provided new capabilities to change the genome. This is a long standing meeting, certain to be thought provoking, animated, and collegial all at once.