The primary objective of this paper is to advance our understanding of inter-organizational learning by introducing evidence of illegal learning across organizational boundaries. By drawing upon data from a largely unexplored area of management and organization studies, that of economic and industrial espionage, we attempt to demonstrate that contemporary debates could benefit considerably from an exploration of such illegal forms of learning. Three vignettes involving economic and industrial espionage are presented to demonstrate the limitations of both our current conceptualisations of inter-organizational learning and what motivates people to illegally acquire knowledge across organizational boundaries. In direct challenge to the dominant 'black-box' view of organizations presupposed by the sticky and leaky knowledge debate these vignettes present powerful evidence of external forces encouraging the forced leakage of knowledge. Resultantly our understanding of what constitutes sticky and leaky knowledge has to be adapted. Finally, we conclude with a discussion of the implications for future research