Marathon • Half-Marathon • Half-Marathon Relay • 5K   |   Historic St. Charles, Missouri   |   Saturday, October 2, and Sunday, October 3, 2021

Race Registration

Check out what’s new in 2021!

In 2020, we set out to give our runners a challenge during the strangest year. And as expected, you brought the heat! MO’ Cowbell runners thrived in The Chuck Challenge so we had to bring it into 2021. We are happy to introduce… MO’ COWBELL CHALLENGE WEEKEND!

What the heck is Challenge Weekend? 

Challenge Weekend is a two-part race and an opportunity to challenge yourself even further. Run our 5K course on Saturday evening AND the marathon, half, or relay on Sunday! You’ll receive an extra medal and extra swag! That’s right, walk away from MO’ Cowbell this year with THREE medals.

Well, that’s cool! Is there more? 

Glad you asked! This year the kiddos get to take part in the running action. We love watching families come to race day festivities and have always dreamed of including the little ones. New in 2021 is our first ever Mini MOO Mile, a one-mile fun run for children 10 and under. All participants will receive a t-shirt and medal. 

Registration DatesFullHalfRelay5KChallenge!Mini Moo Fun Run
March – April$90$70$110$35$35$20
May – July$95$75$120$45$45$25

Race Registration — pay by credit card for the lowest processing fees, immediate confirmation, and quick access to your runner profile! 

Can’t make it to MO’Cowbell, the flattest and fastest race in the St. Louis region? We will miss you but you can still be part of the fun! Sign up today as a Virtual Runner

Virtual Runner (Mail Bib & Medal)Virtual Runner (Mail Bib, Medal & Shirt)

Terms & Conditions
Sale and/or transfer of race entries/bib numbers is strictly prohibited. All entry fees are non-refundable. Registration may be deferred toward a future event with MO’ Cowbell approval prior to race day.  Contact us directly at

Race officials may cancel, delay or change the event in case of extreme weather or other conditions that may affect the safety and health of the participants. In the event of race cancellation, refunds will not be issued. Sale and/or transfer of race entries/bib numbers is strictly prohibited.