Generation Scotland is a Biobank, a resource of biological samples and information on health and lifestyle from thousands of volunteer donors in Scotland. The aim of Generation Scotland is to create an ethically sound, family- and population-based infrastructure to identify the genetic basis of common complex diseases. The Generation Scotland concept has been evolving for several years (see Timeline), and now involves three complementary projects, the Scottish Family Health Study GS:SFHS, Genetic Health in the 21st Century GS:21CGH and the Donor DNA Databank GS:3D. Together these projects have recruited a cohort of over 30,000 people. Generation Scotland is establishing multi-disciplinary skills networks in genetic epidemiology, statistical genetics and health informatics. Social scientists have been involved from the start, conducting a public consultation process and addressing ethical, legal and social issues. The output from these projects will be of value to the biomedical, sociomedicolegal, healthcare and bioindustry sectors. Background The main focus of Generation Scotland is on identifying the inherited factors, or genes, that influence our risk of being affected by a number of common causes of ill health, including heart disease, diabetes, mental illness, obesity, stroke and diseases of the bones and joints. Our genes also influence how we respond to different medicines. The basic idea behind Generation Scotland is that by comparing the genes in large groups of people (such as patients and healthy people, or people who respond well to a medicine and people who do not) researchers will be able to work out which genetic factors contribute to our chances of becoming unwell or of suffering from drug-related side-effects. Common disorders such as heart disease and diabetes are significant causes of chronic ill health and death in middle-aged people. Adverse reactions to prescription drugs delay recovery and drain healthcare resources. Generation Scotland is therefore addressing issues of major public health importance. Disease risk and drug response are examples of complex traits. Instead of having a single cause, complex traits typically result from a combination of factors including genes, environment and lifestyle (diet, smoking history, exercise patterns, use of other medicines etc.). Until very recently there was no efficient way of systematically searching for the genetic factors that underlie complex diseases. However the completion of the Human Genome Project, coupled with technological advances that allow rapid comparison of thousands of DNA samples, means that the necessary methods are now available. Detection of the relevant genetic factors depends on