One of the major figures in the growth of scholastic and collegiate lacrosse in New England, Charles E. Marsters first grew attached to the sport while an undergraduate at Harvard (BS, 1907), but his commitment never waned thereafter. Spurred by his energy and initiative, participation in the sport rose steadily at both the high school and collegiate level, establishing New England as one of the centers of the American game. An officer of the United States Intercollegiate Lacrosse Association (USILA), serving as vice president (1907-1908) and president (1909-1910 and 1917-1918), Marsters worked tirelessly as player, coach, and manager to promote the sport. With Paul Gustafson, he founded the Boston Lacrosse Club in 1913, playing point for sixteen years and managing the team, which became the first in New England to play teams from outside the region. He also laid the foundation for teams at Yale in 1915, and at Brown, MIT, the University of New Hampshire, and Tufts in the later 1920s.

In 1935, Marsters and his colleague Tom Dent founded the New England Intercollegiate Lacrosse League (NEILL), which became a major vehicle for promoting the sport. He was recognized for his labors on behalf of the sport with an award from USILA in 1951 and with induction into the U.S. Lacrosse Hall of Fame as a player in 1957.

The files of the New England Intercollegiate Lacrosse League (NEILL) document the growth of lacrosse in New England from an informal club activity to a regulated, interscholastic and intercollegiate varsity sport. The bulk of the collection consists of correspondence, minutes, and agendas kept by co-founder Charles E. Marsters and a handful of other NEILL officers. Reflective of his enthusiasm for lacrosse, Marsters's correspondents ranged from coaches to regional and national lacrosse associations, as well as college and prep school officials, including Frank Boyden, Headmaster of the Deerfield Academy and trustee of the University of Massachusetts Amherst. Some later correspondence reflects interest in the sport at UMass Amherst, beginning in the 1950s, and the beginnings of women's lacrosse as a collegiate sport.

The NEILL collection is equally valuable in documenting the founding of the Boston Lacrosse Club (1913-1962) through member lists and rosters, reports from the managers and treasurers, and promotional materials. The printed material in the collection includes rule books and news clippings, and materials and correspondence relating to publication of The Lacrosse Guide, as well as copies of the guide itself (1907-1962), and photographs.