The winged mapleleaf, Quadrula fragosa, historically occurred in the Mississippi, Tennessee, Ohio, and Cumberland river drainages, but has suffered severe population and range reductions. At the time that the species was federally listed as endangered, its range was thought to have been reduced to a stretch of the St. Croix River between northwestern Wisconsin and east-central Minnesota. Recently, morphologically “Q. fragosa-like” specimens were discovered at sites in Arkansas (Ouachita River and Saline River), Missouri (Bourbeuse River), and Oklahoma (Little River). Subsequently, a plan was proposed to re-introduce Q. fragosa into portions of its historic range where its been extirpated from within the upper Mississippi River basin. The project objectives were 1.) Recommend the number of “founder” individuals required to generate the same level of genetic diversity in a newly established population as seen in the original population; 2.) In addition, allow for the ability to identify newly recruited juvenile mussels using microsatellite genotyping, and link individuals from the founded population back to the St. Croix River source population.