This study contributes to an understanding of the international growth of small and medium-sized enterprises. Thus, it proposes a learning-based model, which shows the influence that the social capital of the firm over external access and exploitation of knowledge and how this affects entrepreneurial orientation. This model is tested via structural equation modelling (Partial Least Squares) applied to a 178 Spanish international-firms sample. The results of data analysis emphasize, on the one hand, the importance of managing inter-organizational relationships in the firm learning processes and, on the other hand, how knowledge exploitation exerts a significant influence on the firm's entrepreneurial behaviour and, therefore, determines its international expansion.