Above: Coach Tierney, Head Coach of Denver University Men's Lacrosse, talks the importance of box lacrosse.

We Aim to Educate!

Lacrosse is a fast, physical game that demands players make quick decisions on the fly. We stress creativity and understanding of basic concepts, not uncompromising rules and tactics. We give our players the opportunity to make plays.

COSMO Lacrosse was founded on the principals of fun, long term athletic development, and two dad's wanting to spend time with their kids. Coaches Ben and Drew launched our first "club" team in the summer of 2021. Our combined 2028/2029 team played in two local tournaments and played box lacrosse throughout the winter, spring and summer together. Why? Because sport is meant to be fun and we have loved the game of lacrosse since we played as kids in upstate New York (Syracuse, NY). Now, we look to continue to grow the game of lacrosse and not only teach our kids but to grow the game for boys and girls in northern El Paso county because we love the game.

Team COSMO Summer 2022

Denver Shootout, 2nd Place 2028A Division




The boys of COSMO Chaos fall box & field lacrosse are crushing it this fall! Preparing for both Castle Rock Box League playoffs and our field tournaments, including the 7v7 Boomerang and Mile High Harvest. 

October 2 - Boomerang Tournament
Learn more here: Boomerang Tournament Page


October 9 & 16 - CR Box League playoffs
See the CR Box League Current Standings

October 29 & 30 - Mile High Harvest

Learn more here: MHH Tournament Page


DAY 1: Sunday, August 14th (11:00a - 1:00p) 

DAY 2: Tuesday, August 16th (5:30p - 7:30p)

Players wanting to be considered for our Fall teams must attend one or both of the tryout days. Those registered for tryouts will receive an email inviting them to FREE pre-season training to ready them for fall (starts week of July 25th).


LOCATION: Barefoot Park (Roller Coaster & Northgate)


Current 5th - 8th Grade Boys (Two Teams - 5th/6th & 7th/8th)


Castle Rock Box League (Sunday's, September & October)
Boomerang 7v7 Field Tournament (Oct. 2, Littleton)

Mile High Harvest Field Tournament (Oct. 29/30, Arvada)


2 practices/week Aug & Sept, Tuesday & Thursday evening 

1 practice/week October, Saturdays



Custom uniforms

Experienced coaches who have played both field and box with a combined 50+ years of lacrosse experience

Fall 2022 COSMO Coaches:

Drew Stevenson - Head Coach 5th/6th (Asst. 7th/8th)

Ben Holstein - Head Coach 7th/8th (Asst. 5th/6th)

Sean Eells - Assistant Coach, both teams

TBD - Assistant Coach, both teams

To learn more please email 

Fee: Approximately $400, includes 15+ practices and league/tournament fees. Uniform, + $110. Those players who played during Summer '22 for COSMO do not need to purchase a new uniform.


To become a member of US Lacrosse Click Here.

Select "Youth Membership" - it is good for one year, so if you sign up for any other US Lacrosse based program, including all COSMO programs, you will be covered/not have to pay again for a full year.