Spatial familiarity is a significant, yet insufficiently investigated factor that affects wayfinding. The aim of this thesis is to explore spatial familiarity as a dimension of wayfinding, and explain how it affects human behavior within the built environment. Factors affecting wayfinding are defined under two categories; environmental information and individual characteristics. Spatial familiarity is a concept that comprises these two characteristics and thus, is analyzed separately. Factors affecting spatial familiarity apart from those mentioned above are defined as experience, spatial ability, meaning and expectancy, and environmental complexity. The effects of individual and group differences on spatial familiarity are identified and assessed through an empirical study conducted in two buildings of the Faculty of Art, Design, and Architecture, of Bilkent University. Spatial ability tests, wayfinding tasks, and interviews were administered to subjects from the Department of Interior Architecture and Environmental Design and the Department of Graphic Design. The findings indicate that spatial and individual factors affect spatial familiarity with the built environment.