Does Entrepreneurial Orientation (EO) matter to Strategic Alliances (SA) formation? In this study, we call attention to the gap in the management literature of SA by the paradigm of EO to investigate a model where EO is related to the SA; the predecessor, top management entrepreneurial behavior (TMEB), influences the EO–SA relationship; and there is a mediator effect of the company size. The results indicate that improving the risk-taking dimension of EO does matter in promoting SA. If we consider the TMEB as an antecedent of the EO–SA relationship, the EO becomes a highly significant mediator. We also highlight the influence of the company-size mediating role, especially the competitive aggressiveness dimension of EO for small-sized enterprises. In this way, the present research contributes to the extension of works relating to EO and SA by showing that the TMEB has great importance in the EO–SA relationship and to the consolidation of the EO construct by using it in a multidimensional way in a reflexive model. The model used is strong and representative of the entrepreneurship field (that is, 28 per cent of the TMEB–EO–SA relationship). EO matters to SA formation and can be used to increase SA, which can reduce barriers to entry and business risks.