The US National Sheep Improvement Program (NSIP) was established in 1987 and is supported exclusively by US sheep breeders and their organizations. In 2010, limited options for sustainable involvement with US institutions led NSIP to establish a partnership with Meat and Livestock Australia to merge genetic evaluation activities with LAMBPLAN, the Australian sheep genetic evaluation system. Outsourcing genetic evaluation services to LAMBPLAN expanded NSIP resources and increased the frequency of updating of EBV. The operating philosophy of NSIP correspondingly evolved to become a proactive force for genetic improvement of US sheep. LAMBPLAN offers EBV for 85 different traits. NSIP provides EBV for a subset of these traits including body weights from birth through adulthood, reproductive and ewe productivity traits, ultrasonic predictions of fat and loin muscle depths, fleece weight and quality measurements, and worm resistance. LAMBPLAN offers selection indexes for various breeds and production objectives, and NSIP offers indexes specific to US breeds and conditions. NSIP serves all US sheep breeds, and also offers genetic evaluation services for meat goats, but is dominated by 4 groups: (1) Western range breeds (mainly Targhee, Rambouillet and Columbia), (2) terminal sire and other meat breeds (mainly Suffolk, Hampshire, Dorset, and Shropshire), (3) maternal wool breeds (mainly Polypay), and (4) hair sheep breeds (mainly Katahdin). In 2013, 123 flocks submitted data to NSIP. The 4 breed groups each submitted records on 2,700 to 3,200 lambs, and the 9 breeds listed above accounted for over 85% of NSIP flocks. Genetic trends in US breeds document the effectiveness of selection. Use of genomic strategies to increase accuracies of EBV is a major focus of LAMBPLAN research and development, providing opportunity for corresponding activities in NSIP. Detailed phenotypic records of animal performance are increasingly recognized as essential for discovery and validation of genomic markers, and NSIP is increasingly recognized as the most comprehensive repository of sheep data in the US. Storage of DNA from all progeny-tested NSIP sires and a sample of lambs in each major NSIP breed is intended to allow NSIP to make a larger contribution to meeting the research needs of the sheep industry.