This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
District of Columbia requires a bicycle helmet for any rider under the age of 16. The same rule extends to children carried as passengers in a child seat or trailer. Civil violation. The Mayor may impose a fine of up to $25 for a first offense; the fine is waived on proof that the minor has obtained a conforming helmet and completed a bicycle-safety course. See D.C. Code § 50-1606 (Bicycle helmets required for persons under 16).
If you're 16 or older, District of Columbia doesn't require you to wear a helmet by state law. Riders under 16 (and any child carried as a passenger) must wear a helmet that meets the ANSI, Snell or ASTM F1447 (a CPSC-certified helmet satisfies all three). standard.
Cities can be stricter than the state floor, and bike-share systems often require helmets regardless of age. If you're renting or commuting in a major city, confirm the local rule before you ride.