The aims of the present study were to investigate (1) whether antecedents of work‐to‐family conflict identified in previous research have similar effects among knowledge workers, whether work environmental factors, particularly relevant for boundaryless work and not explored previously, affect work‐to‐family conflict in this group, and (2) whether the workplace culture (family friendliness and demands on availability) has a main effect on work‐to‐family conflict and moderates the effects of the work environmental factors. A sample of 396 Danish knowledge workers selected from a national, representative cohort study was followed up after 12 months. Data were analysed with a multiple GLM procedure with and without adjustment for baseline values. The results identified adjustment behavior toward deadlines as an important precursor for the development of conflicts. Further, a family‐friendly workplace culture protected against conflicts and moderated the effect of influence at work. Well‐known antecedents, such as quantitative demands and number of work hours, were further confirmed as relevant also in this specific context. It is concluded that a workload of a suitable size, sustainable behavior related to deadlines, and a family‐friendly workplace culture could potentially improve the likelihood that employees feel confident that they perform successfully both at work and at home.