The advantages of sharing knowledge when participating in a Supply Chain (SC) are well established in the literature, but the challenge of knowledge leakage, and how to manage it, is still in its infancy. In order to increase the understanding of knowledge leakage, when SMEs participate in SCs, this study describes types of knowledge that may leak away, how they are valued, and how knowledge leakage can occur. The result includes two frameworks that also have shown to be potentially useful for examining the maturity of a specific SME with regard to knowledge leakages when participating in the SC.