Some of the important literary qualities of Mrs. Frisby and the Rats of NIMH are the use of humanized animals, character complexity and development, interwoven stories, a flashback technique to vividly portray past events, and a setting that demonstrates themes, personalities, and conflicts. O'Brien presents animals that are "humanized;" that is, they think, feel, speak, and react as humans might. Their conflicts can be seen as analogous to human conflicts.

Mrs. Frisby is a believable character who overcomes her fears to develop a sense of independence. Fear and courage, insensitivity and kindness, all are depicted as facets of a character's complex personality.

The author skillfully interweaves the conflicts of Mrs. Frisby and the rats, not merely through plot, but also through the intricate development of similar themes and conflicts. Although Nicodemus's account of their years at NIMH fills eight chapters, the tale is told through action...