PROJECT SUMMARY Animal models are essential for understanding the mechanisms of development, and for uncovering the early life origins of disease. The utility of these models depends on the effective application of genetic methods to establish causal relationships between genes and phenotypes. The goal of this proposal, targeted to the Office of Research Infrastructure Programs (ORIP), is to build resources that dramatically improve the reproducibility, utility, and efficiency of research in sea urchins - which are used by hundreds of researchers across numerous NIH-supported projects. These resources include modular founder lines (“building blocks”) enabling myriad approaches, from cell and stage-specific mutagenesis to combinatorial fluorescent reporter expression, to active genetics. The Aims of this proposal utilize both traditional (transposon- mediated transgenesis) and modern (CRISPR/Cas9) techniques to meet these diverse needs. Further innovation of the work comes from application of this modular genetic design to a species with the ideal biological features and background of knowledge for transgenesis and research- scale culturing. This work will have transformative impact on research across the mandates of NIH, including studies on reproduction, membrane transport, and gene regulation.