Australian labour history has traditionally neglected non-union firms as an area of research. However, in recent years, in the context of declining union density, labour management practice in non-union firms has become a topical area of contemporary industrial relations debate. At the heart of much of these debates remains the longstanding assumption that management practice in non-union firms can be categorised within a simple dichotomy of either ‘substitution’ or ‘suppression’. This article seeks to rectify this neglect by examining the labour management practices of two non-union firms during the post-World War II period in Australia. Far from being a simple case of ‘substitution’ or ‘suppression’, this article concludes that management action is far more diverse and complex than the simple dichotomy suggests. Furthermore, this article demonstrates that management strategy in non-union firms was contingent on, and shaped by, six factors: the firm’s economic fortunes, management’s approach to industrial relations, the agency of labour, the labour market, the firm ownership and threat of union organising.