This research examined the relationships between work environment (i.e., workload and development opportunities), heavy work investment (i.e., work engagement and workaholism) and work-to-family conflict (WFC) over time. A three-wave longitudinal study was conducted among 464 employees from a Belgian public administration. Workload and opportunities for development at Time 1 were found to be respectively negatively and positively associated with work engagement at Time 2, which in turn was negatively associated with WFC at Time 3. Only workload at Time 1 was positively associated with workaholism at Time 2 which, in turn, was positively associated with WFC at Time 3. In the interests of both organizational effectiveness and employees’ well-being, it is important to identify the work-related variables that influence perceptions of WFC. Moreover, in order to manage human resources effectively in companies, it is important to understand the mechanisms by which the work environment influences WFC.