Prerelease reconditioning improves the chance of survival of rehabilitating raptors. Reconditioning may also help to rehabilitate waterfowl, including those that are threatened or endangered, especially if the birds are released during periods of migration. A flying harness, creance, remote-controlled launcher, and portable tower were used to create a means of reconditioning a rehabilitating 5-month-old female wild mallard duck (Anas platyrhynchos) that had been housed in a rehabilitation center for 7 weeks while recovering from an injury. Pre- and postflight serum lactate levels, body condition index scores, and controlled flight distances were used to assess the bird's degree of conditioning. Postflight serum lactate levels never returned to preflight levels and were not deemed a reliable indicator of physical fitness. However, the mallard showed an increase in endurance and strength as well as improved body condition index scores over the course of the reconditioning program.