the association between POS and anxious symptoms. Conclusions: POS, PsyCap, hope, resilience and optimism could be effective resources for reducing depressive and anxious symptoms. PsyCap, hope, resilience and optimism act as moderators and mediators in the associations of POS with depressive and anxious symptoms. Managers should promote supportive settings and investment in PsyCap to improve workers' mental health. Underground coal mining remains one of the most dangerous occupations worldwide. Underground coal miners have to work in a confined space and perform multiple tasks, and they always face a variety of threats from physical agents, such as noise, vibration, temperature, humidity, and radiation. Additionally, many occupational psychosocial risk factors (e.g., job stress, insufficient social support, interpersonal conflict, work-life interference, and threat perception) are caused by poor production organization and management in underground coal mining 1,2) . The safety and health of underground miners are threatened seriously by their complex working conditions. However, most previous studies mainly focused on physical health of underground miners, and very few studies have paid attention to mental health in this population. Existing research on the mining workforce indicate that they suffer severe mental health problems, especially depression and anxiety 3−5) . Underground coal miners were found to suffer from more severe mental health problems than surface workers from the same coal mine 5) . Thus, more attention should be paid to protection of the mental health of underground miners. China possesses the Abstract: Effective resources for improving mental health among Chinese underground coal miners: Perceived organizational support and psychological capital: Li LIU, et al.