In most societies there are individuals or groups who are not fully integrated into its structure and therefore have a marginal existence within it. These individuals or groups may be deemed not to deserve our attention and concern. This marginality can result from membership of a minority group or can be a consequence of economic disadvantage, visible difference or disability. Often, economic deprivation or poverty unites these disparate groups.

In the UK the Government's commitment to tackle social exclusion shows that it recognises the problem of marginalisation. Social exclusion is defined as ‘the inability of our society to keep all groups and individuals within reach of what we expect as a society and the tendency to push vulnerable people into the least popular places' (Reference PowerPower, 2000). Thus, it is apparent that to be marginal carries the risk, or indeed the certainty, of being excluded from general prosperity. This is of concern to us as doctors and psychiatrists, in particular, because the adverse health and social consequences bear directly on our work. The effects of poverty on childhood disorders are well recognised. The links to crime, homelessness, drug misuse, unemployment, suicide and psychiatric disorder in adulthood are also well established.

A series of papers addressing the psychiatric needs of a number of marginal groups in our society are to be published in APT (see Box 1). These will deal with groups such as homeless children and their families, individuals with sensory impairment, older adults from ethnic minority groups, the poor, asylum-seekers and refugees and prisoners.

Readers may be surprised to see Nolan's paper on the mental health of nurses. The justification for this is simple. Nurses and doctors, by the nature of their occupation, have special needs with regard to access to health care that, in many respects, are indistinguishable from those of other marginal groups in society.

We cannot overstate the importance of adequate services for these marginal groups. The welfare of society in general is intimately linked to that of the significant proportion that is excluded from the commonwealth. These papers seek to draw our attention to the needs of the some of the most deprived members of society.