While telework has become a popular occupational mode, research has found both positive and negative effects on employee outcomes. To reconcile these inconsistent findings, we apply the job demands–resources model and investigate the possible curvilinear effect of telework on innovative and counterproductive work behavior. Analysis of two-wave survey data from South Korean public officials indicates that the relationship between the extent of telework and employee work attitudes is not always positive or negative. We find that telework can be a job resource promoting positive work attitudes, but this beneficial impact decreases and can eventually become negative as employees telework more extensively. Additionally, leader–member exchange relationships play an important moderating role. A high-quality employee–supervisor relationship can enhance the benefits of extensive teleworking, but a low-quality relationship can make the downsides of telework even worse.