How organizations create, transfer, and retain knowledge has been the focus of intensive investigation by management researchers. However, one aspect of the dynamics of knowledge--organizational forgetting--has received comparatively little attention. In this paper, we draw on an exploratory, multiple-case study of learning in international strategic alliances to explore how and why organizations forget. Based on our case study, we develop a theory of organizational forgetting, discuss the role of forgetting in the dynamics of organizational knowledge, and present a typology of types of organizational forgetting. 10.1287/mnsc.1040.0273