BACKGROUND: There has been a trend to implement open space offices: wide-spread office floors with modern and colourful furniture. However, there is limited scientific knowledge on the effects of Open Space Offices (OSO). Studies are scare and show heterogeneous results. OBJECTIVE: By using the Job Demands-Resources model as a conceptual framework, the present study aimed at investigating the influence of subjective and objective features of the OSO (i.e., office size, desk-sharing, openness) next to classical psychosocial working conditions (i.e., demands, resources) on irritation and subjective well-being. METHODS: Cross-sectional and longitudinal data out of four different organisations (490 participants, 43.73 years of age, SD = 12.02) were used. RESULTS: Results showed that both features of the OSO and working conditions play a role in well-being at work. In line with current studies, job demands and resources contributed more to irritation and subjective well-being than features of the OSO. CONCLUSION: The influence of traditional psychosocial working conditions has so far been neglected in research on OSOs. However, their contribution to employees’ well-being next to features of the OSO could explain the heterogeneous findings of the existing research on well-being in OSOs. Thus, when implementing OSOs, employees’ well-being can only be enhanced if working conditions are targeted in parallel.