Massachusetts held special elections on November 5, 2013, deciding 1 legislative seat.
Legislature
- House (160 seats): 131 D, 29 R before the election, 131 D, 29 R after; control stayed with Democrats.
- Senate (40 seats): 36 D, 4 R before the election, 35 D, 4 R, 1 other or vacant after; control stayed with Democrats.
Legislative races
| Race | Winner | Others | Notes |
|---|---|---|---|
| Senate 2nd Hampden and Hampshire | Donald F. Humason, Jr. (R) 52.5% | David M. Bartley (D) 47.3% |