Tle North West of the UK has been described as probably the most important centre of high technology outside the south of England. The aerospace sector is a major UK employer and accordingly, is an important part of the North West economy. However, the aerospaces upply chain approach is changing, ajýd that change impacts on the aerospace manufitcturing small to medium size enterprises( SMEs) in the region. Many aerospacec.o mpaniesa re claiming to be adopting both agile and lean manufacturing principles. Research has indicated thai the knowledgea nd understandingo f agility in aerospaceis modesta nd consequentlyt he difference between lean and agile is not well known. This thesis aims to assessa gile manufacturingw ithin UK aerospacem anufacturingS MEs. The specific objectives are derived to provide focus for the research activities, in order to fulfil the specific aim of the reseaich in a structured and scientific manner. Following an extensive literature survey of agile manufacturing, other relevant manufacturing strategic frameworks, changem anagementr, esponseto changei n manufacturinge nvironmentsa nd aerospaceS MEs a theoreticalm odel of Agile Manufitcturing within the UK aerospaceS MEs has beend eveloped. Ile theoretical model of Agile Manufacturing within the UK aerospace SMEs was used to assess agile manufacturing in four UK aerospace manufacturing SMEs (case study organisations). From an evaluation of the case study organisations and comparisons with the theoretical model, the findings enhance the understanding of Agile Manufacturing theory, concepts and practice. Additionally, the theoretical model presented in this thesis is considered appropriate for use in other aerospace manufacturing SMEs and is presented as a holistic aerospacea gile manufacturinga ssessmentot ol. The research has shown the complexity and interrelationship between four agility enabling integrated sub-systems of agile manufacturing strategy, external motivators, organisational psychology and operational characteristics. The key findings of the research indicate that the case study organisations do not actively promote an agile manufacturing strategy that takes into consideration the organisational psychology and its influence on the performance of the operational characteristics of agility. Likewise, not all the external motivators of agility are considered when developing and deploying their organisations' strategies. Consequently, the role of the agile strategy process, teams and organisational change are considered as important issues that need addressing by these case study organisations.