ABSTRACT The volatility, uncertainty, complexity, and ambiguity that define today’s business environment have pushed companies to build close collaborative relationships to achieve a competitive advantage. In recent years, Horizontal Logistics Collaboration (HLC) has gained significant attention considering its potential in improving performance and facing volatility and uncertainty. However, little attention has been given to the role that partners’ similarity plays in HLC. Considering that collaborating partners are expected to pool their resources and co-organise their operational activities, partners’ similarity plays a vital role in enabling HLC. In this paper, we investigate the role played by partners’ similarity in determining collaboration success. Two models, in which partners’ similarity is considered as an antecedent and then as a moderator are developed and tested. The results show a non-significant moderating effect of partners’ similarity, while its impact on the collaboration activities is significant and positive. This indicates that partners’ similarity plays the role of a precursor to collaboration rather than a facilitator.