Three distinct concepts underlie the notion of religiosity or religious involvement: participation in organized ritual, contact with religious-based social support networks, and spirituality, which refers to the subjective aspects of religious feeling and experience (Hill and Pargament 2003). Religion plays an important role in American society. Nationally representative surveys show that over 80 percent of adults in the United States report a formal religious affiliation and roughly 40 percent of adults report attending religious services once a month or more (General Social Survey 2002; Pew Research Center 2002). A large majority of the numerous studies investigating the relationship between religious involvement and mental and emotional well-being have found a positive association (Koenig et al. 2001). Similarly, many studies have examined the relationship between religious involvement and mental health disorders, and the large majority of these have found that religious involvement is associated with a decreased likelihood of experiencing a mental health disorder. Further, studies of patients with diagnosed psychiatric disorders suggest that religious involvement and religious coping (e.g., prayer, reading inspirational literature) is associated with better mental health outcomes over time (Koenig et al. 1998; Bosworth et al. 2003; Mohr and Huguelet 2004). Less is known about the relationship between religious involvement and the use of formal mental health care. We define formal treatment as care rendered by individuals trained to assess, refer, and treat people with mental or emotional problems and the settings in which these individuals practice. Several studies suggest that although religious providers play a relatively small role in the mental health care delivery system, contact with religious providers represents a key entry point into the formal mental health care system (Narrow et al. 1993; Young et al. 2003; Wang et al. 2004). Epidemiologic data from the National Comorbidity Survey suggest that roughly a quarter of people turned to religious providers first for help with their mental or emotional problems (Wang et al. 2003). The same study shows that the role of religious providers depends on the presence and severity of mental health problems. Wang et al. (2003) that while those with serious mental illness (SMI) comprise 16.3 percent of patients reporting any use of religious providers in the past year, those with SMI comprise only 8.7 percent of those reporting religious providers as their sole source of care. Models of mental health care use conceptualize treatment seeking and the setting in which care is received as an individual choice representing the most desirable option among a set of two or more feasible and/or acceptable alternatives (Frank and Kamlet 1989; Andersen 1995; Pescosolido et al. 1998; Harris and Edlund 2005). In this context, the range of treatment options available to an individual is seen as a function of economic resources, the availability of providers in geographic proximity, one's experiences with the treatment system, and external information obtained through formal sources or learning through the experiences and opinions of others. The relative desirability of alternative treatments is seen as a function of preferences and beliefs about the etiology of mental health problems, and various attributes of care, such as cost, convenience, effectiveness, and stigma associated with use. In integrating religion into this framework, it is important to distinguish three aspects of religion: (1) strength of religious belief, (2) religious participation, and (3) spirituality. In our application, we assess belief strength using measures of the importance of religious beliefs in the respondent's life and the influence of religious beliefs on decision making. We measure religious participation by frequency with which individuals attend church. These measures are described in greater detail in the Methods section. Unfortunately, our data source lacks a distinct measure of spirituality. When mental or emotional problems arise, some individuals may interpret these problems as spiritual, and turn to prayer, reading of scripture and other inspirational works, meditation, and other forms of religious coping rather than formal mental health treatment (Koenig et al. 2001). Further, those who see these problems as mental health or emotional issues may use religious coping in lieu of formal mental health treatment. Individuals who report that their religious beliefs are an important part of their lives may be more likely to see the problem and/or the solution as spiritual and utilize religious coping instead of formal mental health care. We hypothesized H1: Greater importance of religious beliefs and greater influence of religious beliefs on decision making is associated with a lower probability of mental health care use, regardless of the severity of distress. In some cases, religious participation, and all that it entails, may substitute for formal mental health care and reduce the likelihood of the use of such services (Koenig et al. 2001). In this light, religion often offers many of the elements felt to be important in individual and group therapies, such as empathy, advice, emotional support, help in problem solving, positive role models, opportunities for abreaction, and reality testing. These elements occur both in interactions with lay members and clerical counseling. Further, religion involves other factors that may improve mental health which are not traditionally available in formal mental health treatment, such as prayer, opportunities for social interaction and pleasurable activities, financial assistance, and a sense of belonging. For several reasons, it is likely that the substitution of religious involvement for formal mental health care is most successful for those with moderate levels of distress, as opposed to those with high levels of distress. First, while many of the elements of mental health treatment are available in religious settings, those with more serious distress may require help from practitioners with specialized training. Second, psychotropic medications are an important component of care for many individuals with serious distress who may have a psychiatric disorder and are not available through religious involvement. Similarly, specialized psychotherapies, such as cognitive behavioral therapy, are typically delivered only in formal mental health care settings. Finally, the needs of individuals with serious distress may overwhelm the resources of clergy and lay members of social support networks centered around religious institutions and activities. Religious involvement may also facilitate treatment initiation in some cases. Clergy may refer individuals to formal mental health treatment, and because clergy hold positions of authority and are often held in high esteem, their advice to seek formal treatment may be particularly influential. Members of religious-based social support networks may also encourage other members with mental or emotional problems to contact with clergy who may in turn refer to specialty providers. Religious involvement may also expand the range of available formal mental health treatment options. For example, many denominations sponsor and financially support organizations that provide mental health counseling and other social services (e.g., Catholic Family Services, Jewish Social Services) where patients can pay according to an income-based fee schedule. Further, religious institutions may provide financial assistance so that members can receive treatment from mental health providers practicing in the community. Consistent with research suggesting that individuals with SMI rely less exclusively on religious providers compared with their less impaired counterparts (Wang et al. 2003), it is likely that clergy and lay members are more apt to refer those with more serious distress to formal mental health care, while providing clerical counseling and social support to those with less severe disorders. Based on the expectation that the severity of mental health problems moderates the relationship between religious participation and formal mental health care use, we hypothesized H2: More frequent religious service attendance is associated with a lower probability of mental health care use among those with moderate distress. H3: More frequent religious service attendance is associated with a higher probability of mental health care use among those with more serious distress. In this paper, we used nationally representative data from the National Survey on Drug Use and Health to test hypotheses about the associations between formal mental health service use in the past year and measures of religious involvement. To our knowledge, this is the first study to address this topic. Moreover, the data we use to explore these associations are particularly well suited to this application as it allows us to stratify our analysis by level of mental or emotional distress.