PROJECT SUMMARY While mice are essential models for many areas of neuroscience, there are also many aspects of higher brain function and dysfunction that cannot be adequately modeled in rodents. Thus, there is a need for new genetic models that have brain structure and function closer to humans. For these reasons, non-human primates (NHP) provide an attractive model to study higher brain function and brain disorders. A promising emerging NHP model is the common marmoset, a small New World primate that has many advantages as a genetic model. Although the adaptation of bacterial CRISPR/Cas systems for targeted genome engineering and model creation has revolutionized modern biology, editing of the marmoset genome is still in its infancy. Given the significant time and money required for marmoset genome editing, new methods to increase editing efficiency, decrease mosaicism, and identify correctly-edited embryos prior to transfer to recipient females are critical. Additionally, new methods for controlling the zygosity of founder animals are necessary to enable analysis of homozygous F0 animals and to avoid homozygous editing when targeting essential genes that cause embryonic lethality upon biallelic disruption. To these ends, we propose a research program that will significantly enhance our ability to introduce multiple types of edits into the marmoset genome, reduce mosaicism, control the zygosity of edits, and identify successfully edited embryos through prenatal genetic testing. We will disseminate these technologies and models through direct resource sharing, in-person trainings, deposition to NIH-supported Marmoset Coordination Center. Together, the proposed advances will significantly reduce the time, effort, costs and animal numbers necessary to marmoset genetic models and will unlock the true potential of marmosets for basic and translational neuroscience research.