This article aims to (a) explore the impact of witnessing workplace bullying on emotional exhaustion, work-related anxiety, and work-related depression and (b) determine whether the resources of trait optimism, coworker support, and supportive supervisory style buffer the effects of witnessed bullying. In a two-wave study involving 194 employees, we found that witnessing bullying undermined employees' well-being (work-related depression and anxiety) 6 months later, but only if the employees were low in optimism (personal resource) and lacked supervisor support (contextual resource). Strong coworker support weakened the relationship between witnessing bullying and well-being (emotional exhaustion and work-related depression). Our findings demonstrate for the first time some of the factors that protect against the impact of witnessing workplace bullying. Future research should focus on the development of workplace interventions that foster feelings of social support and optimism among employees. (PsycINFO Database Record (c) 2019 APA, all rights reserved).