A number of recent post-occupancy surveys in office buildings have pointedto reduced levels of occupants' satisfation associated with the loss of controlover environmental conditions experienced by many employees who movedfrom private or small group offices into large spaces, often kept at uniformand strictly controlled temperatures. Theoretical formulations in environ-mental stress theory have highlighted the importance control for self-efficacy and competence, and the negative effects that transpire when indi-viduals are not able to negotiate the envrionment in meaningful ways. De-riving from these formulations, increased user control of the workspaceenvironment is advocated on grounds of the enhanced satisfaction and re-warding experience that such an interaction could provide. However, inspite of the possibly significant role it might have in the everyday relationof individuals to their workspace environment, the concept of control hasremaind relatively undifferentiated, with little attention given to the effectsof exercised vs. perceived control and even less to the type and amount ofcontrol actually available across settings.This paper presents and discusses results of a study intended to clarify someof the mechanisms involved in the perception of control over nera by termalconditions at the workplace, and their contingencey upon the resources madeavailable by physical and organizational characteristics of the office envri-onment. Questionnaire and observational data were obtained from 511 officeemployees deployed in a variety of wrkspace arrangements ranging fromprivate offices to large open spaces, both with and without structural parti-tions. The estimation of control opportunities available at the different set-tings followed a detailed procedure involving not only quantifying the num-ber of available features in a given office space (building components andthermal controls) but also apprarsing them in terms of their proximity andaccessibility to the user, as well as of their ceas of operation. Organizationalnorms, varying from rather flexible to restrictive in regard to workspaceorganization and energgy management were also recorded. Subjective ap-praisals of control were evaluated by means of a scale specially developedfor this study.Perceptions of control over the near environment were found to have strongpositiv bearing on expressed satisfaction with the thermal environment. Thedegree of control made available by the physical environment was Instru-mental in enhancing employes' perceptions of control, and indirectlythrough it, satisfaction with the thermal environment. Empirical reltion-ships were established between actual and perceived measures of control, inorder to provide basic information on the control implications of office en-vironments differentially characterized by specific features, such as num-ber of adjustable building components, availability and location of thermalcontrols, and spatial configuration of the workspace layout. This informationcan lead to comparisons of effectiveness of different office design options inincreasing the degreee of conotrol perceived by employees.