Although it cannot conclusively proven, several theories today attempt to explain why the girls became ill. The Reverend Parris' African slave, Tituba, came from the Caribbean had a knowledge of voodoo.

Tituba had previously amused the girls with stories of the paranormal. Some believe that these stories so influenced the girls that they became terrified and sick. Other that the execution of the woman Glower in 1688 gave the idea to Parris’ daughter and started the whole story.

Another theory is that the girls simply wanted attention, and the more attention they got from their antics and their witch stories, the more they continued the deception until they themselves either believed their tale or were too afraid to recant.

Yet another more modern theory suggests that "ergot" (a hallucinogenic fungus in the rye or cereal grains, similar in effects to LSD) caused the girls to convulse and see witches and specters (apparitions or spirits) of witches.