Harold Proshansky is best known as a foundational figure in environmental psychology and for developing the concept of 'place identity.' He argued that place identity is a powerful and often overlooked component of a person's overall identity. It refers to the cognitive and emotional bond that develops between individuals and their physical surroundings. He proposed that people incorporate their environments—homes, neighborhoods, cities—into their sense of self, and that this connection significantly influences their psychological well-being, behavior, and sense of community.

Place identity, as conceptualized by Harold Proshansky, is a sub-structure of one's self-identity that consists of cognitive and affective meanings attached to the physical environment. It is not simply about knowing where one is, but about having an emotional and symbolic connection to a place. This connection forms through sustained interaction and experience, leading a person to view specific places as part of who they are. Proshansky argued that disruptions to these places—through relocation, demolition, or change—could lead to disorientation, grief, and a crisis of identity, highlighting the importance of place in human psychology.

Harold Proshansky spent most of his distinguished academic career at the City University of New York (CUNY) Graduate Center. He joined the faculty in 1963 and was instrumental in founding the Environmental Psychology Ph.D. program there, which became one of the most prominent and influential in the world. As a director of this program for many years, he trained a generation of environmental psychologists. Prior to his time at CUNY, he also held positions at the University of Kansas and the University of Chicago, but it was at CUNY where he made his most significant contributions to the field.

Harold Proshansky authored and edited several foundational works in environmental psychology. His most influential book is 'Environmental Psychology: Man and His Physical Setting,' co-edited with William Ittelson and Leanne Rivlin, first published in 1970. This seminal volume was one of the first comprehensive collections to establish environmental psychology as a distinct scientific discipline. He also published the highly influential paper 'The City and Self-Identity' in 1978, with Abbe Fabian and Robert Kaminoff, which elaborated on his theory of place identity and explored its implications for urban life and urban planning.

Harold Proshansky's work, particularly the concept of place identity, has had a profound influence far beyond psychology. His theories have been widely adopted in urban planning and architecture, where they are used to understand how residents relate to and value their neighborhoods and public spaces. His ideas have also become central to community psychology and social work, informing community development and intervention strategies. Furthermore, his work is foundational in human geography and memory studies, providing a psychological framework for understanding the deep, personal significance that places hold for individuals and communities.

While Harold Proshansky was not a direct student of Kurt Lewin, he was deeply influenced by Lewin's field theory and his emphasis on the person-environment interaction. Proshansky's work can be seen as a continuation of the Lewinian tradition, moving from the abstract conceptualization of the 'life space' to a systematic study of how the physical environment, in particular, shapes identity and behavior. He, along with other early environmental psychologists, translated Lewin's broad principles into a rigorous, empirical science focused on the built environment, using Lewin's ideas to legitimize the study of specific, tangible environments like cities and homes.

Harold Proshansky is a pivotal figure because he helped establish environmental psychology as a legitimate and important sub-discipline within psychology. At a time when psychology was focused on internal processes or isolated stimuli, Proshansky championed the study of complex, real-world physical environments and their profound impact on human identity and mental health. He provided a strong theoretical foundation and institutional home for this field, ensuring its continuity and growth. His work fundamentally expanded the scope of psychology, reminding the field that human behavior and selfhood are inextricably tied to the places we inhabit.