This RFA is an initiative of the NIH Blueprint for Neuroscience Research (http://neuroscienceblueprint.nih.gov), a trans-NIH partnership to accelerate neuroscience research. Fifteen Institutes and Centers are participating in the Neuroscience Blueprint. This RFA will be administered by the NIMH on behalf of the Neuroscience Blueprint. This funding opportunity supports the design, creation, and characterization of recombinase-expressing C57BL/6 mouse lines to aid in studies of nervous system development and/or function. These so-called “driver lines” should specify expression in distinct cell types and/or other useful temporospatial expression patterns in the nervous system. Drivers with the greatest utility (such as inducibility) and relevance to neuroscience research will be given priority. Applicants should have the capability to create and validate a minimum of 10 novel driver lines in the funding period specified.