Emil Kraepelin introduced the concept of dementia praecox in 1893. The eventual acceptance of the concept brought a degree of clarity and order previously unknown to psychiatric nosology. The pre-Kraepelin era had been dominated by concepts such as mania, melancholia and adolescent insanity. After Kraepelin these ideas were abandoned in favour of the two great concepts of dementia praecox and manic depressive insanity, both of which remain active within modern psychiatry in the fonn of schizophrenia and bipolar disorder. This two-part study focuses on the early British reaction to Kraepelin's concept, from 1893, when he first introduced it, to 1913 when it gained general recognition. It examines the struggle experienced by the proponents of dementia praecox before the concept's acceptance by most British psychiatrists in 1913. It argues that both clinical/professional and linguistic factors influenced the British response to dementia praecox. Part 1 of this study describes the backdrop to the development of Kraepelin's ideas and examines the response to the concept in the British psychiatric textbooks and journals of the period. Part 2 will explore reaction to the concept in the professional meetings of the period, and will also examine and evaluate the key issues arising from the debate. 1. In this paper, unless otherwise stated, all references to Kraepelin's work are to the English translations of his books.