Chelsea provides a range of opportunities for interscholastic competition.
Students compete in the Delaney Athletic Conference on sports teams, including volleyball, soccer, cross-country, basketball, and tennis.
Each year Chelsea participates in the Shenandoah Valley Regional Science Fair held at James Madison University.
A select group of Chelsea students belongs to the Mu Alpha Theta National Mathematics Honor Society and competes in its contests throughout the school year. Chelsea students have also attended Mu Alpha Theta summer conventions in Boston, Orlando, and San Diego.
Middle School students participate in the regional MathCounts competition each year.
Chelsea students compete in Poetry Out Loud, a national recitation contest.