The purpose of this study is to investigate the outcomes of a manufacturer involving its suppliers in their lean training program. A single in-depth case study is conducted to examine a lean training program that was offered by Scania to five suppliers. Semi-structured interviews were conducted at Scania and these suppliers to explore the outcomes of the training program. The interview findings were triangulated by completing observations and focus groups at the suppliers. Four main outcomes are identified after the completion of the training program. First, the suppliers became easier to collaborate with due to better internal ways of working and more trust in terms of reliability. Second, the suppliers improved their ability to identify possible problems that could jeopardize deliveries. Third, the suppliers improved their delivery precision. Fourth and finally, financially unstable suppliers were less perceptive to the lean training program than financially stable suppliers. This study also proposes avenues for future research.