This reference work is in two parts. The first is a biographical dictionary of the 325 men who played in the National Association between 1871 and 1875, with their playing record, together with what we know of their other baseball experience and their lives beyond baseball.

The book also contains a dictionary of the 25 clubs who participated in the league, showing their history, their management, their uniforms and logos, their home grounds, and their performance in the league.

About 150 player photographs are included and each club entry has two or three supporting images (18 are historical maps). Bibliography and index.