This thesis examines the relationship between computer-based technological innovation and the integration of design and manufacture. Central to this thesis is some new empirical evidence drawn from two case studies of computer aided design innovation in engineering organisations which manufacture high technology, electronics-based products. The focus of attention throughout this dissertation is the extent to which middle and senior engineering managers affect, and are affected by, both the innovation process itself and the type and form of technical and organisational integration achieved through technological change. Recent research in the field of technological change has argued that one of the most important characteristics of computer-based systems is their 'integration' potential. However, there is little detailed understanding concerning the nature of this integration nor of its realisation in practice. This thesis contends that integration occurs in one, of both, of two senses (technical and organisational), and that in each case it occurs at a point along the continuum between two types (full and partial) and two forms (weak and strong). The thesis also suggests that the nature of the integration achieved is directly influenced by the degree of involvement and commitment of the 'dominant coalition' in the early innovation process stages, the relative power of different interest groups within management, and the continuity of management control and authority across all process stages. The case studies examine the innovation process by breaking it down into a series of analytically distinct stages. It is argued that initiation is a separate and significant stage, distinct from the decision to introduce, and that the initiation objectives have downstream effects on the innovation process and the integration that results. It is also argued, with respect to CAD innovation, that there is no such state as 'routine' operation as suggested by many recent studies of technological change. In practice, there is continuous enhancement and implementation, and system operation can, therefore, only be defined at specific points in time. The thesis concludes that the integration potential of CAD systems can only be realised in a strong and full technical and organisational sense if a new breed of engineer and engineering manager evolves.