This pamphlet provides a brief overview of the operations conducted at the Great Lakes Naval Training Station at Great Lakes, Illinois as well as the Service School that operated within the facility. It was published between 1943 and 1945 according to when R. R. M. Emmet, then a Captain, was commanding officer of the training station. Short descriptions of the history and functions of the Training Station and Service School give the reader a basic understanding of what went on at a Navy training facility during WW2 and what newly inducted men experienced while stationed there. The Service School section lists the specialist trades taught there along with the prospective ratings that could be earned upon completion of the school coursework. Each rating description includes the name of the rating, an illustration of the specialty mark, the duties entailed with each rating, examples of related civil jobs, and additional practical knowledge that would help with doing the particular job. The specialty mark appeared on the rating badge of petty officers and sometimes on the uniform by itself in which case it was called a distinguishing mark. The illustrations and descriptions provided by this booklet help collectors and historians better understand the symbols that appear on Navy uniforms along with the duties, responsibilities, and training those symbols convey.