Seventh-day Adventism is inextricably linked with the life and ministry of Ellen G. White, co-founder of this nineteenth-century denomination. This thesis examines her position and role in the Seventhday Adventist church both in her lifetime and, since her death in 1915, through her voluminous writings, which have been carefully preserved and widely distributed. This study seeks to present up to date source material on Ellen G. White in categorised, documented form and thus to provide a wider knowledge of her work and views. While recognising that her ministry was to the Seventh-day Adventists primarily, this thesis indicates areas In which it is considered that she also contributes insights of value to the Christian Church generally, especially in her eschatological emphasis which is central in her teaching. After a survey of the historical backgrounds of the denomination's development, aspects of the Adventists' Dogmengeschichte particularly influenced by Ellen G. White are considered analytically and critically, especially in the areas of Scriptural authority, race relations, and ecumenism, since these are subjects of contemporary significance. Ellen G. White remains a controversial figure because of her claims to be distinctly "a messenger of the Lord" and because her denomination considers her to have functioned in a prophetic role. The consequences and criticisms of these claims are examined throughout the thesis and her relevance both to Adventism and the wider religious spheres assessed. It is argued that the passage of time and the general ecumenical climate of today make possible a more dispassionate study of Ellen G. White's work and insights. This thesis is designed, hopefully, as a further contribution to ecumenical understanding as her character, purposes, and teachings are more clearly discerned.