The Louisville Twin Study (LTS) was started in 1957 by Dr Frank Falkner, who was Chair of the Department of Pediatrics at the University of Louisville School of Medicine. The Louisville Twin Study was internationally recognized as one of the oldest, largest, and most comprehensive studies of child development related to multiple birth status and is unique because of the extensive, longitudinal assessments and because of the relatively low rate of mobility out of the Louisville area. Due to difficulties with securing funding, the LTS began closing in 1999. Data collection continued until the final closure in 2000 and has been on indefinite hiatus. In 2008, Dr Deborah Winders Davis was appointed as Director of the LTS.