Book excerpt: The Interpersonal-Psychological Theory of Attempted and Completed Suicide was published by Professor Thomas Joiner in 2005. This book is a critique of this theory with emphasis on whether or not it is a new theory of suicide, omissions in the literature Dr. Joiner reviewed to formulate the theory, the theory monumental task to explain the deaths of certain victims of 9/11 as suicides rather than homicides resulting from the al-Qaida terrorists attacks, violations of fundamental assumptions in qualitative and quantitative studies supporting the main tenet of the theory, and the problem of empirically testing core assumptions in the theory.