Physical activity (PA) and sedentary behaviour (SB) are important factors in individual health and wellbeing. Organisations can benefit from workers who are physically active and have low levels of SB, as they have reduced stress and absenteeism, improved productivity, and improved wellbeing. Many people now operate in a work environment where employees have flexible working hours or are able to work from home on a regular basis. These flexible working arrangements could influence employees’ PA and SB, and contemporary health promotion must adapt to suit this new work context. However, few studies have investigated the impact of workplace flexibility on PA, and no studies have assessed the impact on SB. There is a need to understand how traditionally successful behaviour changes strategies to improve PA and reduce SB can be applied in a flexible work environment. The aim of this research program was to understand and positively influence PA and SB in office-based employees engaged in flexible work practices. The objectives were to assess the associations between flexible work and PA and SB, identify intervention priorities and potential strategies relevant to a flexible workplace, and deliver an intervention for employees with flexible working practices. This research program comprised four studies and to date has produced three peer-reviewed publications. All data were collected from staff in a financial services organisation based in Brisbane, Australia. [...]