Fritz Klein (sex researcher)
Fred "Fritz" Klein (December 27, 1932 – May 24, 2006) was an American psychiatrist and sex researcher who studied bisexuals and their relationships. He helped begin a foundation that promoted bisexual culture. He was an author and editor, as well as the developer of the Klein Sexual Orientation Grid a scale that measures an individual's sexual orientation. Klein believed that sexual orientation changed over the course of a lifetime and that researches underestimated the number of men that had sexual interactions with both sexes. He was a proponent of using Neurolinguistic programming to change behavior.
Life and career 
He received a BA from Yeshiva University in 1953, and an MBA from Columbia University in 1955. He studied medicine at University of Bern in Switzerland for six years, receiving his MD in 1961. He practiced as a psychiatrist in New York City in the 1970s.
Self-identified as bisexual, Klein was surprised at the lack of literature on his sexuality in the New York Public Library in 1974. He was inspired to place an advertisement in a New York City alternative newspaper the Village Voice and founded a ground-breaking social and support group for the Bisexual Community called Bisexual Forum.
Klein Sexual Orientation Grid and other works 
He devised the Klein Sexual Orientation Grid, a multi-dimensional system for describing complex sexual orientation, similar to the "zero-to-six" scale Kinsey scale used by Alfred Kinsey, but measuring seven different vectors of sexual orientation and identity (sexual attractions, sexual behavior, sexual fantasies, emotional preference, social preference, lifestyle and self-identification) separately, as they relate person's past, present and ideal future.
Klein published The Bisexual Option: A Concept of One Hundred Percent Intimacy in 1978, based on his research, the world's first real psychological study of bisexuality. He also co-authored The Male, His Body, His Sex in 1978. Klein moved to San Diego in 1982. He published Bisexualities: Theory and Research in 1986. In 1998 he founded the American Institute of Bisexuality (AIB), also known as the Bisexual Foundation, to encourage, support and assist research and education about bisexuality. Klein also founded the Journal of Bisexuality. He remained the Journal's principal editor until his death. He published Bisexual and Gay Husbands: Their Stories, Their Words in 2001. Klein published a novel, Life, Sex and the Pursuit of Happiness in 2005.
In 2006 Klein was diagnosed with cancer, and underwent surgery as a result. Although expected to die from cancer in matter of months, Fritz Klein instead died at home in San Diego, California, from cardiac arrest aged 73. He was survived by two brothers and his life partner, Tom Reise. Klein donated his body to science.
See also 
- Pearce, Jeremy (June 4, 2006). Fritz Klein, 73, Psychiatrist Who Studied Bisexual Culture, Dies. New York Times
- Who's your Daddy! by Sheela Lambert. Bi Magazine (1974). From web.archive.org
- Associated Press (June 6, 2006). Fritz Klein, 73, noted expert on bisexual life. Newsday
- Staff report (16 June 2006). Fritz Klein: Psychiatrist driven to prove the existence of bisexuality.The Times,
- Reed, Christopher (June 19, 2006). Fritz Klein: Psychiatrist exploring the complexities of bisexuality. The Guardian, 19 June 2006
- Lee, Ryan (June 2, 2006). Noted bisexual leader Klein dies at 73. Washington Blade (via archive.org)
- Buchanan, Wyatt (June 1, 2006). Dr. Fritz Klein -- bisexual pioneer who created Klein Grid sex scale. San Francisco Chronicle
- American Institute of Bisexuality (bisexual.org)
- The Klein Sexual Orientation Grid (via bisexual.org)
- AIB Mourns the Death of Founder, Dr. Fritz Klein (bisexual.org, via archive.org)
- 'Who's your Daddy!' by Sheela Lambert (Bi Magazine, via archive.org)
- Sexual and Affectional Orientation and Identity Scales by Bobbi Keppel & Alan Hamilton for the Bisexual Resource Center (via archive.org)