Registration for the 113th running of the Boston Marathon, set for April 20, 2009, is under way.

Registration kicked off at 9 a.m. Wednesday. The field will be limited to the first 25,000 entries, so runners are encouraged to sign up quickly.

Runners who have met the designated qualifying time for their age group on or after September 29, 2007, at a certified marathon may register. In addition to online registration, runners can download a PDF application at www.baa.org or request a paper application by emailing registration@baa.org. Entries will be accepted until the field is full.