Substantial energy savings can be achieved by reducing energy use in office buildings. The reported study used a Theory of Planned Behavior (TPB) model extended with perceived habit to explain office energy-saving behaviors. One aim was to examine if organizational contextual variability independently predicted office energy-saving behaviors over and above TPB variables and self-reported habit. Another aim was to examine the relative predictive value of TPB variables and habit for energy-saving behaviors between organizational contexts. Survey data on energy-saving behaviors, TPB variables, and habit and number of office mates were collected from office workers of four organizations in the Netherlands. The results indicate that intention was the strongest direct predictor of the behaviors printing smaller and not printing e-mails, whereas habit was the strongest predictor of the behaviors switching off lights and switching off monitors. Of the social-cognitive factors, attitude was the strongest predictor of intentions overall. The effect of perceived norm varied widely between behaviors and subgroups. Number of office mates had a direct, unmediated effect on the behavior switching off lights and a mediated effect via attitude and perceived control. The effect of organizational contextual variability on behavior was entirely mediated through the psychosocial factors for the two 'printing behaviors', but only partially for the two 'switching behaviors'. The relative predictive value of habit and intention differed between organizations. The findings suggest that organizational contextual variability has unconscious influences on some office energy-saving behaviors. Interventions should take variation in the relative importance of cognitive factors and habit between behaviors, and to a lesser extent between organizational contexts, into account.