Definitions of sexual orientation are reflections of theoretical positions within the essentialist versus social constructionist debate. A cognitive sociological approach to analyzing the positions within this debate allows theorists and researchers to be aware of three distinct theoretical positions or thought communities: natural kinds thought community, social kinds thought community, and empty kinds thought community. Standard content analysis and grounded theory methods are used to analyze the principles, strategies, and practices each thought community uses to mark group membership into various sexual categories. The analysis reveals that each theoretical perspective is marking group membership differently.