Twin Falls Idaho is a 1999 independent drama directed by Michael Polish, who co-wrote and co-stars in the film with Mark Polish. It premiered at the 1999 Sundance Film Festival and was acquired by Sony Pictures Classics, who gave the film a limited release on July 30, 1999.

The film portrays the lives of shy conjoined twins Blake and Francis Falls, who take residence in a rundown hotel to hopefully reunite with their estranged birth mother. They find their gateway to the outside world through an eccentric young prostitute named Penny. They agree to attend a Halloween party with Penny and pretend to be wearing a "Siamese Twins" costume.

The rest of the movie involves the brothers dealing with Francis's health problems, the changing relationship between the brothers, and Blake's budding relationship with Penny. Ultimately, Francis's health deteriorates too far and the twins have to be separated. Francis is too sick to survive and dies, but Blake survives and must begin a life apart from his twin. Penny visits him and the two start a relationship.

The film has a 78% "Fresh" rating on Rotten Tomatoes based on 46 critics’ reviews.^[1]

Critic Roger Ebert gave the film four out of four stars, writing "It is one of those films not much interested in plot, but is fascinated by what it is like to be somebody, or two somebodies. The movie doesn't depend on special effects to create a shared body..and instead uses the performances."^[3] He added, "We can imagine [the brothers’] lifetime of isolation from the normal things people do", and concluded "In its quiet, dark, claustrophobic way, this is one of the best films of the year."^[3]

Janet Maslin of The New York Times said, "It's a film that dwells as hauntingly on loneliness as it does on never actually being able to be alone", and that Mark Polish gives an "especially affecting performance.”^[4]