This thesis explores the histories of mild to moderate depression and the use of over the counter (OTC) St. John’s wort (St. John’s wort) during the 1990s. In doing so it not only investigates the diagnosis and definition of mental illnesses, it also raises questions about the interface between conventional and alternative medicine. Using a variety of printed sources, including popular media articles, scientific and medical journal publications, and St. John’s wort self-help books, a number of historical themes are explored. This thesis takes issue with existing medical historical studies of depression. Firstly it is argued that they have presented progressive depression histories. Secondly, it is suggested that they have retrospectively diagnosed depression on the basis of similar symptoms. It is therefore argued that illness is specific to the time in which it exists and should be understood within its own historical timeframe. During the 1990s standardised St. John’s wort was promoted as a natural and safe remedy. Adverts and media reports also highlighted the fact that it had a long medical history. Although this thesis establishes that the plant has been traditionally used to treat physical illnesses, it seems that a growing distrust of conventional antidepressants, combined with an established interest in alternative medicine, encouraged some lay people to use the remedy to treat mild mood disorders. It is further argued that lay people have a history of self-treating minor mental illnesses using preparatory and OTC remedies such as preparatory nerve tonics. Not only did lay people desire autonomous treatments, it also seems that standardised St. John’s wort provided a functional role as an OTC remedy. By the 1990s the concepts of responsible self-care and self-treatment were being actively encouraged by medical authorities. Therefore this thesis reclassifies the passive mild to moderately depressed patient as an active consumer. Following an analysis of the popular media it is suggested that the 1990s coverage of depression and its treatments was confusing. Indeed, depression and its treatment with conventional medicines and St. John’s wort were sometimes presented as part of a wider life style choice. Finally, it is argued that by the 1990s standardised St. John’s wort received the same scientific and medical scrutiny as conventional medicines. It is therefore suggested that the remedy represents a situation in which the boundaries between conventional and alternative medicines have become increasingly indistinguishable.