The goal of the NIH-funded Knockout Mouse Project (KOMP) is to generate a comprehensive resource of null mutant alleles, with a reporter, using gene targeting mutagenesis in mouse strain C57BL/6. The construction of the KOMP mutant collection is being funded in projects submitted in response to RFA-HG-05-007 and RFA-DA-06-009. The purpose of this Funding Opportunity Announcement (FOA) is to establish a resource repository to collect and archive the null mutant alleles, primarily in the form of cryo-preserved embryonic stem (ES) cells, as well as associated DNA constructs, and cryo-preserved embryos or live mice created by the KOMP. The successful KOMP repository should aim to become self supporting over time.