A behaviour setting can be viewed as a small-scale social system comprising people and inanimate components (Barker, 1968). Various components within the temporal and spatial boundaries of the system interact in an orderly and highly regulated fashion to fulfil essential setting functions. As a result of constant person-environment interaction, behaviour settings become associated with particular patterns of behaviour (Bechtel, 1982). Thus, analyzing the behavioural patterns occurring within each setting can help to understand and evaluate the impact of the physical aspects of the setting in relation to its key functions and objectives. The present study applies behaviour setting theory to the evaluation of a workplace environment. Conceiving of the environment in behaviour setting terms makes it clear that physical features of the workplace environment and behaviour patterns within the enclosure must be closely interrelated. Thus, workspaces and facilities must not only create a desired mood or atmosphere but also facilitate actions of people for organizational purposes. Using Behaviour Setting Analysis (eliciting subjective occupant accounts combined with observations of objective patterns of behavior), the study looks at the overall environment-behavior fit of a behavior setting as a workplace system in relation to setting functions and organizational goals. The setting of particular interest is an open plan office environment in a University Library, staffed by people who have recently been migrated from a set of closed group offices. In particular, the present study assesses the open plan office environment in relation to physical structure (arrangement of the groups in an open space, individual workstation boundaries and activities, facility use and locations, privacy issues and physical distractions), interpersonal and social relationships, and the attitudes and perceptions among office users. In addition, the study will compare the working environments before and after physical changes, to enable an evaluation over a 6 month period of time, the effect of the change on the individuals, groups, and organization as a whole. The open setting consists of about 25 regular occupants from 4~5 different groups. As a comparative study between pre and post office occupancy, data gathering will take place once in early October 2003 and another in April, 2004 (6 months later): a) individual interview, b) sociometry questionnaire via email, c) activity survey questionnaire via email, d) behavior setting survey, e) office photographs and floor drawing, f) interview with keypersons, and g) document references. Overall, the objectives of the study are 1) to describe key behavioral characteristics of office users in relation to the office environment, 2) to identify social and physical variables from the environment that affect or interact with the office users’ cognitions, motivations, and social processes, 3) to assess the structure of social interactions among individuals as well as groups, 4) to assess the interdependence and boundaries among workstations and facilities, 5) thus, to evaluate the overall environment-behavior fit in the workplace system for the setting functions and organizational goals.