- Who
- Boy Scouts of America , Three Fires Council
- What
- 275 people
- Where
- United States (Willowbrook)
- When
The largest welding lesson consists of 275 participants, achieved by Three Fires Council and Boy Scouts of America (both USA) in Willowbrook, Illinois, USA on 11 April 2015.
The lesson was attempted in order to help scouts from various groups to achieve their welding merit badge.