In this paper we examine the influence of strategic technology alliances on organisational learning. From an empirical perspective we examine the pre- and post-alliance knowledge bases of allying firms. We find that the pre-alliance knowledge base overlap of the allying firms has an inverted U-shaped relationship with the degree of learning taking place in the alliance. Alliances established for the purpose of learning also show a significantly greater increase in knowledge base overlap for the allying firms than for non-learning alliance or non-allying firms. This shows the particular importance of learning alliances as a vehicle for organisational learning and competence development. Contrary to what we expected we found that weak ties are more important than strong ties in organisational learning within strategic alliances.