June 3rd  |  June 17th  |  July 8th  |  Aug 5th  |  Aug 19th  |  Sep 2nd  |  Sep 16th

NEW POLICY FOR Sep. 16th race: Get vaccinated or mask up. 

All event participants must either provide proof of vaccination or wear a mask at the Thursday Sep. 16th race and party. To save time at check-in, please upload a photo of your CDC vaccination card by Wednesday Sep. 15th. Otherwise, please bring it (or a copy, or your mask) to the event.

Vaccinated entrants will receive a wristband at check-in. Anyone without a wristband will be required to wear a mask at all times, including during the race. Per City of Cambridge restrictions, a mask must also be worn indoors regardless of vaccination status. All RACE Cancer Foundation staff and volunteers at the event will be vaccinated.

Join us on seven Thursday evenings from June through September for fun, friendly, chip-timed 5K runs to kick cancer’s butt. Each (of the first six dates) starts with a Women’s 5K, followed by the Open 5K ~30 minutes later. (no Women's 5K on Sep. 16th)

All races are held at a new location, the American Legion Marsh Post #442 in Cambridge, MA, and run on paths along the Charles River. Each event will include a post-race party at the Marsh Post with beer generously provided by Mighty Squirrel. 100% of the event proceeds go to charity, including a portion to the American Legion Marsh Post. RACE Cancer Foundation’s Boston 5K Summer Series also provides funding for the Sunscreen Squad, bringing free sunscreen to outdoor events across Massachusetts.

Sign up for each 2021 Boston 5K Summer Series race at!