The Scouting program in America has always included uniforms for its members and volunteers to identify members and show they are part of the Boy Scouts of America. Scouts and leaders should wear their uniforms to all patrol meetings, troop meetings, and scout outings.
The tan and green Boy Scout uniform is a well-known symbol of American scouting. All scouts in the program wear the same uniform with the major differences being the badges each scout has earned and the troop specific neckerchief.
The official dress uniform is commonly referred to as the 'Class A' uniform but, officially known as the "Field Uniform". Most scout troops also have an "activity uniform", referred to as 'Class B' which is often a t-shirt customized just for the troop. Activity uniforms are worn for work projects, sporting activities, and other events in which the dress uniform might get damaged.
See BSAUniforms.org for details or this PDF file.
Official short sleeve shirt
Official scout pants or shorts (optional)
Official BSA tweed belt
Official BSA cap
Troop 337 neckerchief and slide
Boy Scout Handbook
Troop 337 Field Activity T-shirt
Troop 337 Field Activity cap (optional)
Boy Scout Handbook