Nationals Roster & Staff
Transactions
| Date | Transaction |
| 07/31/09 | Washington Nationals Traded 1B Nick Johnson to Florida Marlins and Jacksonville Suns Traded LHP Aaron Thompson to Nationals Organization. |
| 07/31/09 | Washington Nationals Traded LHP Joe Beimel to Colorado Rockies; Colorado Rockies Traded RHP Ryan Mattheus to Washington Nationals and Asheville Tourists Traded RHP Robinson Fabian to Hagerstown Suns. |
| 07/31/09 | Washington Nationals Traded LHP Joe Beimel to Colorado Rockies; Colorado Rockies Traded RHP Ryan Mattheus to Washington Nationals and Asheville Tourists Traded RHP Robinson Fabian to Hagerstown Suns. |
| 07/31/09 | Washington Nationals selected the contract of RHP Jorge Sosa from Syracuse Chiefs. |
| 07/31/09 | Washington Nationals recalled Elijah Dukes from Syracuse Chiefs. |
| 07/29/09 | Washington Nationals released CF Corey Patterson. |
| 07/23/09 | Washington Nationals placed RHP Jordan Zimmermann on the 15-day disabled list retroactive to July 19, 2009. Right elbow discomfort. |
| 07/23/09 | Washington Nationals recalled Collin Balester from Syracuse Chiefs. |
| 07/21/09 | Washington Nationals signed CF Jose Norberto. |
| 07/20/09 | A.J. Morris assigned to GCL Nationals from Washington Nationals. |
| 07/20/09 | Washington Nationals selected the contract of J.D. Martin from Syracuse Chiefs. |
| 07/20/09 | Washington Nationals selected the contract of RHP Logan Kensing from Syracuse Chiefs. |
| 07/20/09 | Washington Nationals placed LHP Scott Olsen on the 15-day disabled list retroactive to July 11, 2009. Sore left shoulder. |
| 07/20/09 | Washington Nationals designated Julian Tavarez for assignment. |
| 07/16/09 | Washington Nationals recalled RHP Garrett Mock from Syracuse Chiefs. |
| 07/15/09 | Paul Applebee assigned to GCL Nationals from Washington Nationals. |
| 07/13/09 | Washington Nationals optioned Ross Detwiler to Syracuse Chiefs. |
| 07/08/09 | Washington Nationals optioned Matt Chico to Harrisburg Senators. |
| 07/04/09 | Washington Nationals recalled RHP Jason Bergmann from Syracuse Chiefs. |
| 07/04/09 | Washington Nationals designated Jesus Colome for assignment. |
| 07/01/09 | Washington Nationals optioned Elijah Dukes to Syracuse Chiefs. |
| 07/01/09 | Washington Nationals signed LHP Paul Applebee. |
| 07/01/09 | 2B Jeff Kobernus assigned to Vermont Lake Monsters from Washington Nationals. |
| 07/01/09 | Washington Nationals signed RHP A.J. Morris. |