Young et al. BMC Public Health 2011, 11:874 http://www.biomedcentral.com/1471-2458/11/874 correlated with at least one form of substance use and, given the associations between school connectedness and psychological health, it is plausible these measures of school environment may be associated with suicide attempts and self-harm. School context can refer to both aggregate measures of individual perceptions of school connectedness (as described above) and more ‘objective’ characteristics of the school - something that is a true property of the school such as its size, roll, or denomination. In both educational and health research, school size is a factor related to school involvement, alienation and isolation [3]; smaller schools tend to be associated with smaller communities and may provide a more ‘connected’ envir- onment with greater opportunity to ‘know’ both tea- chers and fellow pupils [20]. A counterargument is that, while larger schools may be less cohesive they offer greater educational variety and the opportunity for pupils to develop more specialised and supportive ciques with similar interests. Within the West of Scotland context, the link between individual religion and school is an atypical one, because in some regions Scottish schools are partially stratified according to their pupil’s religious background. In gen- eral, pupils from a Catholic background attend what are termed denominational schools, although this is not pre- scriptive and a minority of pupils from non-catholic backgrounds do attend denominational schools. Non- denominational schools on the other hand make no dis- tinction on religious grounds and accept pupils from any religious background, although, within the West of Scotland the majority of pupils come from a nominally Protestant or ‘Church of Scotland’ background. In gen- eral, pupil religion and school religious denomination match, thus pupils with Catholic parents attend Catholic schools, while pupils with protestant parents attend non-denominational schools. However, within the West of Scotland this does not happen in every case and a minority (3-4%, denominationally mismatched pupils) do not conform to this pattern, Thus, due to a range of circumstances, a minority of pupils who would normally attend a non-denominational school, attend a Catholic school, and a minority of Catholic pupils attend a non- denominational school. In respect of school denomina- tion, individual religion or religiosity is (generally) con- sidered to lower the risk of, those without a religious preferences or minority religions developing mental health problems, but whether or how school and indivi- dual religion interact is unknown [21-23]. Religion, mental health and suicide risk Despite secular trends, religion and religious institutions remain an enduring component of individuals’ lives and both are linked to mental health in a complex fashion Page 3 of 15 [17,18]. Although the evidence is not indisputable, the overall conclusion is that religious belief or religiosity is ‘good’ for mental health and reduces suicide-risk, although the exact mechanisms are unclear [22]. Among the likely explanations are moral prohibition (most reli- gions explicitly prohibit or disapprove of suicide), improved coping mechanisms (a hopeful or positive orientation), increased social support (associated with religious institutions and communities), increased sense of community (through shared values and orientation) and increased pastoral care [21-23]. The link between regular church attendance and men- tal health at age 11 was explored in analyses based on the dataset which forms the basis of this paper [23]. This demonstrated that church attendance interacted with religious denomination, such that weekly (com- pared with less frequent) church attendance was asso- ciated with a mental health advantage (increased self- esteem and reduced anxiety or depression) for Catholics or disadvantage for children with a Church of Scotland affiliation. To date, the bulk of research on mental health and religion has been focused at the individual level and an important remaining task is to differentiate between the individual and contextual effects of religion. In other words, we need to contrast the effects of a reli- gious belief with the effects of living within a religious environment. The two influences are usually con- founded, but our school study can partially disentangle these components. Psychological and sociological the- ories stress the importance of such contextual factors and their likely mechanism of influence. The ecological-transactional framework One major psychological theory that incorporates con- textual influence is the ecological-transactional model (E-TM). The E-TM has been used to explain a range of behaviours affected by ecological context such as child maltreatment [24], community violence [25], sexual behaviour [26] and most relevant to the current study, suicidal behaviours [27]. Briefly, E-TM explains beha- viour on four distinct hierarchically ordered, but inter- acting, ‘ecological levels’; specifically macrosystem; exosystem; microsystem and ontogenic levels. The macrosystem focuses on overarching or societal level factors such as general values and cultural beliefs. The exosystem emphasises the influence of intermediate, but still large social groupings such as neighbourhoods and communities, typically measuring factors such as com- munity norms and exposure to risk at the neighbour- hood level. The microsystem concentrates on the influence of smaller social groups and communities, which can vary dramatically in size, but includes struc- tures such as school, peer group and, at the finest level, family groups. Examples of risk factors at this level are