1991 Score is an 893 card set released in two series of 442 and 451 cards, respectively. It is best known for it's massive size (the largest baseball card set released to date) and 11 subsets: Rookie Prospects (331-379), First Draft Picks (380-391), AL All-Stars (392-401), Master Blasters (402-406), K-Men (407-411), Rifleman (412-416).
Notable Rookie Cards in the set include Carl Everett and Mike Mussina.