This article addresses unexplored questions related to why and when employees' experience of work overload might spur their knowledge hiding behaviour, in a process mediated by family-unfriendly time demands and moderated by a competitive organisational climate. Two-wave, time-lagged data, collected from employees in multiple industries, reveal that a notable reason that excessive work pressures escalate into enhanced knowledge hiding is that employees believe they have to put their jobs before their family lives. This mediating role of family-unfriendly time demands is particularly salient in the presence of performanceoriented organisational climates. For human resource managers, this research underscores a critical factorthe sense that employees have to sacrifice their family lives for workthrough which excessive work pressures may lead employees to conceal valuable knowledge. It also reveals how this risk can be subdued by an organisational culture that avoids a strict focus on performance comparisons across employees.