We study how competitive mechanisms of external knowledge acquisition affect the emergence of collaborative modes of learning. Specifically, we link the hiring of R&D scientists from competing firms to the subsequent formation of collaborative agreements between these firms – in our setting technology oriented alliances and licensing agreements. Using data on inventor mobility and alliance formation amongst 42 global pharmaceutical over 16 years we are able to show that inventor mobility in fact increases the likelihood of alliance formation in periods following inventor moves. Moreover, our results suggest that this effect becomes more pronounced if more productive inventors are recruited but weaker if the recruiting firm is already familiar with the inventor’s prior employer’s technological capabilities. These findings are more robust for alliances that aim at joint R&D efforts than for pure licensing agreements.