Colin Middleton (1910-1983) was regarded as one of the most significant painters working in Ireland throughout his career, yet the assessment of his reputation is now confused and problematic. Middleton's unique characteristics as a painter and his complex development throughout a long career have not been easy to place within histories of Irish art and as a result he has become a more peripheral figure. This thesis aims to counter certain critical perceptions of Colin Middleton and to provide a more appropriate and accurate context for his work. Central to this is the construction of a detailed biography, within which I have given prominence to the environment of his youth in late industrial Belfast. This is crucial in understanding the relationship between his training and work as a designer within the linen industry and his continuing development as a painter. It also demonstrates the need for a reassessment of the history of art in Ulster, including its relationship to industrial development, as well as to indigenous cultural traditions and contemporary art in Britain and Ireland. By bringing together a detailed analysis of primary and secondary material with a wideranging examination of his work, I assert the centrality of Middleton's position within Ireland as a painter whose work responds to many aspects of the society in which he lived. I will be looking at significant figures within Middleton's life, such as John Hewitt, John Middleton Murry and Victor Waddington, as well as artists who were his contemporaries such as John Luke, Nevill Johnson and Daniel O'Neill. I intend to demonstrate the unity of his work across his career and to present the coherence in his development by explaining the personal motivations that drove changes in style and subject matter. In particular, I will connect these to the enduring dialectic between Middleton's changing creative personalities as a designer and as an artist, analysing his achievement as a modernist painter working in a provincial location throughout the twentieth century.