This thesis examines the question of the extent to which the concept of a National Style dominated architectural production in Finland between 1890 and 1916. The thesis maintains that National Style ideas should be understood as one of a number of impulses emerging in Finnish architecture in the 1890s. This point is explored through analysis of the writings of the architect, journalist and Finnish nationalist Vilho Penttilä. His writings reveal that alongside the National Style he was also concerned with the general question of architectural reform in Finland. This thinking included new ideas on the role that materials, construction and new technology should play in shaping architectural design. Alongside this ran interest in the development of a new language of architectural ornament capable of expressing the character of the building and the society who used it. International architecture was frequently referred to as a model in relation to the National Style and architectural reform in general. Comparison is made to other writings within the Finnish architectural press. The thesis is tested through the examination of a case study: the buildings of Penttilä for the National Joint-Stock Bank [KOP] and the architecture of financial buildings in general, with further comparison made, where relevant, to the broader architectural field. This allows for the comparison of the work of a large number of architects and prestigious projects throughout the country. The study reveals that, just as was indicated through the analysis of architectural journalism, National Style ideas were explored alongside other concerns related to architectural reform. National Style features began to disappear in the mid-1900s, subsumed within the drive to find new architectural forms to reflect the modern age and Finland's hopes for the future. This was found to be the case even in relation to Penttilä's work for KOP, where both the architect and the institution were committed to the Finnish nationalist movement.