Many organizations today have CSR policies in place. CSR refers to an organization’s discretionary initiatives that maintain and contribute to social welfare and the environment. However, organizations often fail to implement their CSR policy in practice. As employees play a central role in the implementation of an organization’s CSR policy, the lack of employees’ CSR engagement is a possible explanation. Therefore, successfully engaging employees in CSR programs is one of the key challenges responsible organizations are facing today. Recently, several studies have called for more research on understanding what enhances employees’ CSR engagement. Researchers point out CSR communication as a key antecedent to be investigated in this context. This research project aims to increase our understanding of mechanisms and boundary conditions that explain how and when CSR communication influences employee CSR engagement. First, this project sheds light on which content characteristics in CSR communication promote employees’ CSR engagement. Second, it investigates whether the source of CSR communication can also influence employees' CSR engagement. Third, this research project investigates mechanisms and boundary conditions that influence the relationship between CSR communication and employees’ CSR engagement. To do so, it employs a quantitative research design including an experimental survey study, an experimental field study, and a multi-level longitudinal study.