Although helping behaviors have increased in importance as work has become more interdependent, employees may be hesitant to help others for fear of it affecting their ability to complete their own tasks. Drawing from social learning theory and self-determination theory, we propose and test a multilevel model that examines the effects of supervisor prosocial motivation and psychological safety on employee psychological safety, thriving, and helping behaviors. Using data collected from 245 employees and 83 supervisors, the results of our study demonstrate support for a positive relationship between supervisor psychological safety and employee psychological safety. We also found positive indirect effects of supervisor prosocial motivation on employee psychological safety. Finally, we found that the relationship between employee psychological safety and both helping behaviors and task performance occurred indirectly through employee thriving. We discuss the theoretical and practical implications of our findings and also make suggestions for future research directions.