Research into workplace mentoring is primarily focused on the experiences and perceptions of individuals involved in the relationship, while there is scarcely any research focusing on the impact of mentoring relationships on their social environment. This exploratory research aims to give insight into how coworkers' perceptions and experiences of informal mentoring relationships in their workgroup are related to their perceptions of workgroup functioning. The results of 21 semistructured interviews show that coworkers believe that mentoring relationships affect their workgroup's functioning by influencing both their workgroup's performance and climate. Coworkers applied an instrumental perspective and described how they think that mentoring relationships both improve and hinder their workgroup's performance as they influence the individual functioning of mentor and protégé, the workgroup's efficiency, and organizational outcomes. Furthermore, coworkers applied a relational perspective and described how mentoring relationships may influence their workgroup's climate in primarily negative ways as they may be perceived as a subgroup, cause feelings of distrust and envy, and are associated with power issues. The results of this study emphasize the importance of studying mentoring relationships in their broader organizational context and set the groundwork for future research on mentoring relationships in workgroups.